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ORIGINAL ARTICLES |
From the Department of Psychiatry, University of California, San Diego and Veterans Affairs, San Diego Healthcare System, San Diego, California.
Address reprint requests to: Sonia Ancoli-Israel, PhD, Department of Psychiatry 116A, VASDHS, 3350 La Jolla Village Drive, San Diego, CA 92161. Email: sancoliisrael{at}ucsd.edu
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Key Words: sleep disorders • insomnia • circadian rhythms • sleep hygiene • aging • Bible
Abbreviations: REM = rapid eye movement;; NREM = nonrapid eye movement;
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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When God began to create heaven and earth—the earth being unformed and void, with darkness over the surface of the deep and a wind from God sweeping over the water. God said, "Let there be light"; and there was light. God saw that the light was good, and God separated the light from the darkness. God called the light Day, and the darkness He called Night. And there was evening and there was morning, a first day (Genesis 1:1–5).
There is a long history of sleep and dreams that antedates the growth of sleep physiology research. The Biblical tradition suggests that even at the very formation of life, God created rhythms to control the world, understanding that it would be necessary for the rhythm of light and darkness to exist before plants and animals and man could survive. Today we know that light is necessary for our sleep/wake rhythms to stay intact. And we know that darkness is also necessary. It is the light and the dark that tell our bodies when to secrete hormones or when to sleep.
The Jewish tradition is especially rich in written testimony going back thousands of years. What else might the Bible and the Talmud2 tell us about sleep and sleep disorders? Whereas other religious traditions might also be rich with references to sleep, this reviews only what the Bible and the Talmud tell us about sleep problems. This article uses the Bible and Talmud as historical texts that reflect conceptions of sleep not dissimilar to those established by contemporary formal sleep research.
Sleep disorders are particularly common with approximately one third of adults complaining of insomnia (1), and 9% of middle-aged men, 4% of middle-aged women (2), and 24% of older adults having sleep-disordered breathing (3). With such a large number of the population at risk today, one wonders what complaints were common before modern discoveries of these disorders. Our ancestors had much to tell us about many things. What did they have to say about sleep? This article summarizes one classical tradition in terms of how it conceptualized sleep and the problems associated with it. Understanding the classic texts may help us better interpret what we know today, put into perspective how far we have come, and clarify what questions we still need to ask.
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Gifts of Sleep and Wake |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Another aspect of sleep refers to dreams or sleep sent by God for special purposes or revelations. The first mention of sleep in Genesis, the first book of the Bible, is such a case, when Adam’s rib was removed to create Eve. God "caused a deep sleep to fall on Adam, and he slept..." (Genesis 2:21). This reference to sleep suggests that sleep represents different levels of consciousness, including that level of consciousness (or unconsciousness) achieved with anesthesia. There are multiple references to dreams sent by God in the Bible, including the famous dream of Jacob (Genesis 28:11–15) and the dreams of Pharaoh, so miraculously interpreted by Joseph (Genesis 41:25–32). Because much has been written about dreams (for examples, see Harris (8)), this article will not dwell on dreams, but rather will deal with sleep and sleep disorders.
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Stages of Sleep |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Although the different stages of sleep were first documented in the laboratory in the 1950s (10, 11), there are references to different states of sleep in the Talmud. Thousands of years ago, it was already believed that sleep was not one continuous state. Rabbi Yosi, when discussing when it is permissible to eat on Passover, gives a rather accurate description of stage 1 sleep:
If they fell into a light sleep, they may eat; if they fell fast asleep, they must not eat. What is meant by "a light sleep"?— said R. Ashi. A sleep which is not sleep, a wakefulness which is not wakefulness, eg, if he answers when called, cannot make a reasoned statement, yet recollect when reminded (Talmud Pesahim 120b).
Different Hebrew words, as used to describe sleep in different parts of the Bible, correspond to what we know today as the different stages of sleep (12–14). Tenumah often is used to mean drowsy, which could refer to dosing off or lighter sleep [ie, stage 1 sleep (eg, Isaiah 5:27; Psalm 76:6)]. Yashen and shenah are used to refer to conscious thought that becomes unconscious and involuntary, words that could also describe stage 2 sleep (eg, Genesis 28:16). Radum implies a heavy or deep sleep [ie, stages 3 and 4 sleep (eg, Jonah 1:5, 6)] or is often also used for sleep that is divinely induced, that is, sleep that is involuntary, such as the sleep of Adam when his rib was removed (eg, Genesis 2:21). The last stage of sleep, tardemah refers to a period where the flow of thoughts continue in dreams or in revelation, a perfect description of REM sleep (eg, Genesis 15:12).
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Function of Sleep |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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They [God and the earth] agreed to divide [the task] between themselves: the night was for the Holy One, blessed be He, and the day [was apportioned] to the earth. What did the Holy One, blessed be He, do? He created the sleep of life, so that man lies down and sleeps while He sustains him and heals him and [gives] him life and repose (Pirqe D’Rabbi Eliezer 12:7, 8).
A more recent scientific theory combines past ideas into a two-process model, the homeostatic process, which is the restorative component of sleep and a circadian rhythm component (16, 17). The rabbis, too, may have had an understanding of sleep as a homeostatic process. The Talmud explains that the wise person finds the balance between sleep and wakefulness (activity) (5):
Rabbi Simeon ben Eleazar said: "And, behold, it was very good" means, and, behold, sleep was good. Is there any sleep which is very good! Did we not learn thus: ...a man sometimes sleeps a little and arises and toils much in the study of Torah (Genesis R. 9:6).
The rabbis were implying that sleep at night is very good because it allows the student to be alert enough to study throughout the day (12), ie, like the homoeostatic theory that suggests that the drive for sleep builds up during the waking state and is alleviated by sleep, or in other words, the more we sleep, the more alert we are the next day (17, 18).
Healing is also believed to be a function of sleep. "Sleep is like food and medicine to the sick" (Pirkei de Rabbi Eliezer) (19). "Sleep is the best medicine. It strengthens the natural forces and diminishes the injurious fluids" (Sefer Shaashu’im 9) (19). The Talmud lists six actions that will heal a sick person, one of which is sleep. Sleep is considered to be good, for when a sick person sleeps, he gets well (Talmud Berachot 57b) (20). As it is written: "I should have slept; then had I been at rest" (Job 3:13). Sleep, in fact, is considered so important for an ill person, that, although it is a sin to turn off a light on the Sabbath, it is not considered a sin if it is done so as not to awaken a sick person. In addition, it is taught that if you visit a patient in the hospital, and the patient is asleep, you should not disturb him (Rosh al Hatorah, Vayeira), reinforcing that nothing else is as important as sleep for the healing process (21).
The theory that it is important to let a sick patient sleep has been recently investigated in the laboratory. Spiegel et al. (22) examined whether chronic sleep loss has an adverse effect on health. They found that glucose tolerance and thyrotropin concentrations were lower, evening cortisol concentrations were higher, and sympathetic nervous system activity increased in a sleep-debt condition compared with a fully rested condition. The authors concluded that sleep debt, or not getting enough sleep, had a negative effect on endocrine function with the effects being similar to those seen in normal aging. Not sleeping sufficiently at night may, therefore, increase the severity of age-related chronic disorders.
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Sleep Deprivation |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Although they may not have known why, the Rabbis must have been aware that sleep deprivation has negative effects, for they emphasized the absolute importance of sleep by considering abstinence from sleep a sin. "He that stays awake at night imperils his own life" (Talmud Avot 3:4–5), "because sleep is enforced by nature" (Talmud Tamid 28a) (20). The discussion continues with Rabbi Judah explaining that the "night was only created for sleep" and Rabbi Nachman bar Isaac stating that humans were meant to work during the day (Talmud Eruvin 65a). For this reason, "If someone swears not to sleep for three days, he is flogged..." (Proverbs 6:10, 11). In addition to implying that sleep is necessary, this verse is also interpreted to mean that the person must be lying, as the rabbis believed it would be impossible to remain awake for 3 days (21). Scientific data support the rabbis’ belief that it is impossible to stay awake for so long. Rechtshaffen and Bergmann (26) studied sleep derivation in rats and found that after 2 weeks of sleep deprivation, the rats show a reliable syndrome that included, but was not limited to, temperature changes, heat-seeking behavior, increased food intake but weight loss, increased metabolic rate, and increased plasma norepinephrine. The sleep-deprived rats also showed stereotypic ulcerative and hyperkeratotic lesions localized to the tail and plantar surfaces of the paws; all died within a matter of weeks.
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Excessive Daytime Sleepiness |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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The Talmud suggests that excessive sleepiness is caused in part by food. Being tired after a meal is well known (Talmud Yoma 18a): "The stomach when full induces sleep" (Talmud Berachot 61b) (20). On certain holidays when the High Priest was not allowed to sleep, he was not allowed to eat a large meal either, so that he would not get tired and be tempted to sleep (see "Circadian Rhythms" for further discussion about the effect of midday meals on sleep).
Excessive sleep or sleeping too much is often seen as being synonymous with laziness and sloth (Proverbs 6:9–11; 10:5; 19:15; 20:13; 24:33,34; 26:14). Some examples of these allusions include, "How long will you lie there, lazybones; When will you wake from your sleep? A bit more sleep, a bit more slumber, a bit more hugging yourself in bed, and poverty will come calling on you..." (Proverbs 6:9–11), and "Laziness induces sleep" (Proverbs 19:15). And if one becomes obligated to another, "Give your eyes no sleep, your pupils no slumber" (Proverbs 6:4) until your obligation is fulfilled.
When people are so drowsy that it becomes difficult to function, their ability to work is affected and their quality of life is reduced (27)—as it says in Proverbs, "Drowsiness shall clothe a man with rags" (Proverbs 23:21). These same allusions have been applied to patients with undiagnosed sleep disorders such as sleep apnea or narcolepsy, where the patient often does want to sleep all day and is often accused of being lazy. It is unknown how common narcolepsy or sleep apnea were thousands of years ago, but there is no reason to believe that they were any less common then than they are today.
There were also suggestions on how to treat the problem of excessive sleepiness. To overcome excessive sleepiness, the Mishnah says,
If he sought to slumber, young priests would snap their middle finger before him and say: Sir High Priest, arise and drive the sleep away. Thus once on the pavement, they would keep him amused until the time for the slaughtering [of the daily morning offering] would approach. (Talmud Yoma 20a).
The Gemara explains that "some of the worthiest of Jerusalem did not go to sleep all the night in order that the high priest might hear the reverberating noise [of the people awake around him, singing and amusing him] and so that sleep should not overcome him suddenly." Priests used to prick themselves with a thorn to stay awake (Talmud Gittin 84a) or walk about on the cold marble floor (Talmud Yoma 1:7) (20). This explanation is similar to the phenomenon known today as masking which occurs when the environment is stimulating enough to fool (mask) people into thinking they are alert, ie, keeping them awake even when they are excessively sleepy. When the situation is unmasked and the environment is no longer stimulating, for example sitting in a dark lecture hall, then the person is overcome by sleep. This situation often arises with sleepy drivers who turn up the volume on the radio or open their windows to try to wake themselves up. Snapping fingers and making noises only keeps people awake temporarily. The only way to treat sleepiness effectively, however, is by getting enough sleep. This discussion points out that the rabbis were aware that sleep is not always controllable. No matter how much someone may want to stay awake, when they are tired and the situation is unmasked, sleep can be overwhelming.
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Insomnia |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Insomnia, in general, was no stranger to the rabbis and so, it is no surprise that there are also lessons about problems falling and staying asleep. Sleeplessness, or insomnia, is sometimes used in the Bible to stress the severity of whatever is wrong with a person. One example occurs in Psalms, "I lie awake, I am like a lonely bird" (Psalms 102:8). Loneliness is a common experience for people with complaints of insomnia because they are all alone and awake in the night while the rest of their world is asleep. In addition to loneliness, a guilty conscience can also lead to insomnia. In the book of Esther, "Sleep deserted the king [Ahasuerus]" when he realized he had not rewarded his wife’s uncle, Mordecai, after Mordecai had saved his (the king’s) life (Esther 6:1), whereas in the book of Daniel, King Darius’ "sleep fled from him" after he threw Daniel into the den of lions (Daniel 6:19) (20).
Anxiety and stress are known to cause insomnia and anxiety and sleeplessness are tied together many times in the Bible (eg, Psalm 127:2; Proverbs 4:16; 5:11; 8:16,17). Other instances of difficulty sleeping because of anxiety, distress, and longing are found in Isaiah 26:9 ("At night I yearn for You with all my being, I seek You with all the spirit within me"); in Psalm 6:7,8 ("I am weary with groaning; every night I drench my bed, I melt my couch in tears"); in Psalm 77:4–7 ("I call on God to mind, I moan, I complain, my spirit fails, You have held my eyelids open; I am overwrought, I cannot speak"); in Talmud Sanhedrin 100b ("anxiety on his part, he cannot sleep at night"); in Ecclesiastes 2:23 ("All his days his thoughts are grief and heartache, and even at night his mind has no respite"); and in Ecclesiastes 8:16 ("For I have set my mind to learn wisdom and to observe the business that goes on in the world—even to the extent of going without sleep day and night..."). Job (Job 7:3–4) complained of "nights of misery" where "When I lie down, I think, when shall I rise? Night drags on and I am sated with tossings till morning twilight." This is a typical complaint of many people with insomnia, ie, spending the night worrying about not being able to sleep, about when they will need to wake up, and tossing and turning all night.
Treatments of insomnia today include teaching patients to deal with their worries before bedtime. In the American’s busy life, often the first opportunity to sit quietly and think is when they get into bed at night, which is the wrong time to start worrying. Clinicians, therefore, suggest that patients set aside a "worry time," that is, a time earlier in the day when they can sit quietly and think about their worries. This is one of the effective behavioral treatments for dealing with the anxiety that leads to insomnia (28).
Yet another reference to difficulty sleeping appears in Job (Job 30:17), "By night my bones feel gnawed; my sinews never rest." Another translation is, "my arteries pulsate so strongly that I cannot sleep" (20). This may have been a reference to pain or some other illness causing insomnia. There are other references to illness and sleeplessness in other books of the Bible:
a) Only from daybreak to nightfall was I kept whole, then it was as though a lion were breaking all my bones; I cried out until morning. I piped like a swift or a swallow, I moaned like a dove, as my eyes, all worn, looked to heaven: "My Lord, I am in straits; Be my surety!" What can I say? He promised me and it is He who has wrought it. All my sleep had fled because of the bitterness of my soul (Isaiah 38:12–15).b) For my days have vanished like smoke and my bones are charred like a hearth. My body is stricken and withered like grass; too wasted to eat my food; on account of my vehement groaning, my bones show through my skin. I am like a great owl in the wilderness, an owl among the ruins. I lie awake; I am like a lone bird on a roof (Psalm 102:4–8).
Today it is known that many illnesses causing discomfort disrupt sleep, such as arthritis, cancer, chronic heart failure, many neurological disorders, and chronic obstructive pulmonary disease. Doctors need to consider treating the primary problem (such as the pain caused by arthritis), before, or at least at minimum, when treating the complaint of insomnia (29).
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Treatment of Insomnia |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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In Talmud Shabbat (67a-67b) it suggests, "One may go out with...a fox’s tooth, which is worn on account of sleep; a living [fox’s] for one who sleeps [too much], a dead [fox’s] for him who cannot sleep." Physical activity is also suggested as a cure. In Ecclesiastes, we are told, "Sweet is the sleep of a laboring man, whether he eat little or much...but the rich man’s abundance doesn’t let him sleep" (Ecclesiastes 5:11). There are several interpretations of this passage. One interpretation is that the rich man worries about losing his riches, and thus, also loses sleep (21). Another interpretation is that sleep is a blessing set on the laborer by God, thus to soften his difficult life (4, 31). Today’s research supplies yet another explanation. Studies have shown that increased exercise or physical activity improves sleep (32). The laboring man who is physically active will likely sleep better than the rich man who spends his time counting his money.
There are other suggestions for treating insomnia. One suggestion is to turn out the light (Talmud Shabbat 2:5) (20). Today this would be understood as providing the darkness needed to stimulate the secretion of melatonin (a hormone produced in the pineal gland that induces sleep) (33). There is also a detailed description of how to create the soft sound of dripping water by raising water into the air from a container with a spout that had a double siphon, and allowing the water to slowly trickle out from the other siphon (Talmud Eruvin 104a; Tosefta Shabbat 2:8) (20). This is not very different from white-noise generators sold today or devices that produce the sound of the ocean or other sounds thought to be relaxing. The use of hypnotics was also not unknown; during a case of abdominal surgery (for obesity), a sleeping potion was given to Rabbi Eleazar (Talmud Baba Metzia 83b–84a) (20).
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Sleep Hygiene |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Duration of sleep.
Maimonides, one of the greatest Jewish philosophers as well as a physician, and considered by some to be the greatest Talmudic authority of the Middle Ages, said,
A day and night are twenty-four hours. It is sufficient if you sleep one-third of that, ie, eight hours...You should not sleep face down or face up, only on your side. The first part of the night you should lie on your left side, the latter part of the night on your right side. Don’t sleep immediately after eating; wait about three or four hours before going to sleep. And don’t sleep in the daytime (Hilchot Dei’ot 4:4–5) (19–21).
Post-Talmudic writers determined that 8 hours of sleep were needed, in general, although there could be individual differences (20). The same advice is given today. It is generally recommended that each person get 8 to 9 hours of sleep to be fully functional during the day. Epidemiological data suggest that people who sleep less than 6 hours or more than 10 hours have shorter survival (35).
Timing of sleep.
The sources also advise on the best timing of sleep and wake. "Eight hours of sleep, terminating at dawn..." (Maimonides, Hilchot De’ot, 4:4–5). In several verses of the Psalms, it says: "Awake, O my soul! Awake, O harp and lyre! I will wake the dawn" (Psalm 57:9; 108:3), suggesting that the right time to arise is with the morning sun. "Rab Judah observed: night was created for naught but sleep" (Talmud Eruvin 65a). Time to sleep was governed by the timing of prayer, specifically, for the reciting of the Shema, (one of the oldest and most important of the Hebrew prayers, which affirms Israel’s faith), first thing in the morning and last thing at the end of day. "Rabbi Dosa ben Harkinas says: Morning sleep, and midday wine...drive a man out of the world" (Avot 3:14) (36, 37). Another source has a rabbi commenting, "Sleeping away the morning hours and indulging in strong drink dull the mind" (Talmud Aboth 3:10) (20, 21). The interpretation of this advice is that "man should not willfully sleep late" so that the time of reciting the Shema passes. Perhaps they also intrinsically understood that it is important to get up at the same time each day to keep the circadian clock synchronized. As we know today, not sleeping late and getting up at the same time each day contributes to good sleep hygiene and robust circadian rhythms.
Comfort.
There are multiple references in the Bible to a comfortable temperature being necessary for proper sleep. Jacob, during his exodus, complains of extreme temperatures robbing him of sleep: "Often scorching heat ravaged me by day and frost by night; and sleep fled from my eyes" (Genesis 31:30), and again in similar words in Deuteronomy (24:12–13), God commands that "If you take your neighbor’s garment in pledge, you must return it to him before the sun sets, it is his only clothing, the sole covering for his skin. In what else shall he sleep?" (Exodus 22:25, 26). Although the issue is this law and not temperature, it certainly also teaches us about the relationship between temperature and sleep. Yet another reference to keeping warm and comfortable during sleep is found when, as part of an analogy, the rabbis use an example of a physician telling a patient not to drink anything cold and not to sleep in a damp place (20) or to "rub his temples with oil and sleep in the sun" (Talmud Sabbath 129a).
Alcohol and food.
Although alcohol is often used by insomniacs to help them fall asleep, later in the night, the alcohol causes insomnia (38). There are many references to wine and sleeplessness in the Bible.
Rami b. Abba stated: "A mile’s walk or a little sleep removes the effects of wine." The Rabbi replied: "This applies only to one who has drunk one quarter of a log [a Hebrew measure], but if one has drunk more than a quarter, a walk would only cause him more fatigue and sleep would produce more intoxication" (Talmud Eruvin 64b, Talmud Ta’anith 17b, Talmud Sanhedrin 22b).
They were clearly aware of the effect of alcohol on sleep, and of sleep on alcohol. Drinking a little makes you sleepy, but drinking a lot and then sleeping makes you feel worse, because the sleep is disturbed secondary to the alcohol.
The effect of specific foods on sleep is also noted, in particular, among other foods, milk, fishbrine, and wine should be avoided (20). This advise is repeated in Talmud Moed Katan, where it is advised that "after eating fish, cress, and milk, occupy your body [ie, go for a walk] and not your bed" (Talmud Moed Katan 11a) (20). This agrees with the current thinking about milk and fish containing tryptophan, an amino acid known to have sleep-promoting properties (39).
Napping.
A natural time to take a nap is in the afternoon when our core body temperature dips. For people with insomnia however, an afternoon nap may interfere with nighttime sleep. Although not recommended in the Talmud, napping in the midafternoon, particularly when it is warm, is a practice sometimes seen in the Bible. Abraham, David, and Ishboseth all slept in the afternoon. "He [Abraham] was sitting at the entrance of the tent [sleeping] as the day grew hot" (Genesis 18:1). [Although we are not told that Abraham was sleeping, we are told that it was hot and it was afternoon, and Abraham continues telling the visitors, "bathe your feet and recline under tree" (Genesis 18:4). One interpretation, therefore, is that because Abraham invites his visitors to recline, he too has been taking a nap.] "Late one afternoon, David rose from his couch and strolled on the roof of the royal palaces..." (II Samuel 11:2). "And they reached the home of Ishboseth at the heat of the day, when he was taking his midday rest" (II Samuel 4:5). Even animals rest at noon, "Tell me, you whom I love so well; where do you pasture your sheep: Where do you rest them at noon?" (Songs of Songs 1:7).
Maimonides however, recommended, "don’t sleep in the daytime" (Hilchot Dei’ot 4:4,5) (21). Bursztyn et al. (40, 41) have shown that blood pressure declines during afternoon naps in the same way as it declines during sleep at night and that the siesta, or afternoon nap, is an independent predictor of mortality. The Talmud in general, is against naps on all days but the Sabbath, because daytime is a time for study, not sleep. In the Talmud, Rabbi Eliezer and Rabbi Yochanan ben Zakkai are both praised for only dozing off in the house of study on the Sabbath, but never on any other day (Talmud Sukkah 28a) (20). Sleeping on the Sabbath, the day of rest, is considered a joy. That joy of napping on the weekends is still held by many today, primarily because people think it makes up for the sleep deprivation of the previous week.
There is also a discussion about how long the nap should last if one does nap. "A man may indulge in casual sleep while wearing his tefillin, but not in regular sleep" (Talmud Sukkah 26a-26b). The discussion continues,
What constitutes casual sleep? [Sleeping during the time] it takes to walk one hundred cubits. They continue, "It is forbidden for a man to sleep by day [when it is one’s duty to study the Torah] more than the sleep of a horse. And what is the sleep of a horse? Sixty respirations."
In one commentary, 60 respirations took about one-half hour (20). Although the rabbis meant that a man should not take long naps because he is supposed to be studying, in fact, the same advice is given today. Good sleep hygiene rules advise trying to avoid naps, but if you do nap, limit the length of naps to one-half hour, because longer naps adversely affect the ability to sleep at night.
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Circadian Rhythms |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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He made the moon to mark the seasons; the sun knows when to set. You bring on darkness and it is night, when all the beasts of the forests stir...When the sun rises, they come home and couch in their dens. Man then goes out to his work, to his labor until the evening (Ps 104:19–23).
This confirms that man is diurnal, rising with the light and going to sleep with the dark, whereas some animals are nocturnal, rising at night and going to sleep with the light. This also points out that there is a rhythm to life and that sleep is part of the rhythm, ie, circadian rhythms.
Sleep is controlled, in part, by our core body temperature rhythm, which as it drops at night causes us to fall asleep and as it rises in the morning causes us to wake up (42). In Talmud Shabbat we are told, "Lend me your robe and I will sleep in it. He singed it, wrapped himself therein and slept. As he became heated through and got up, it fell away from him bit by bit" (Talmud Shabbat 110b). Temperature, particularly keeping warm during sleep, is also seen as an approach to healing. The Talmud suggests that an ill person "wrap himself in his cloak and sleep, and he must not be disturbed till he wakes himself. When he wakes, he must remove his cloak, otherwise the illness will return" (Talmud Gittin 70a). In both examples, a person needs to wrap himself up at night to keep warm as his body temperature drops, but needs to unwrap to stay cool as body temperature rises.
As mentioned in "Sleep Hygiene," the rabbis also believe that food brings about sleep, particularly heavy meals: "as a heavy meal conduces to sleep" (Talmud Pesachim 110a); "Eat much because food brings about sleep" (Talmud Yoma 18a). During those eras, the large meal of the day was often eaten during midday. Therefore, the rabbis believed that it was the heavy meal that made them sleepy in the afternoon. Today it is known that core body temperature takes a dip in the afternoon, causing the sleepiness often experienced in the midafternoon.
Sections of the commentaries also refer to circadian rhythm shifts. Research and clinical work in the area of circadian rhythms has shown that it is easier to delay one’s circadian rhythm than to advance it. For example, it is easier to travel west than east and rotating shift workers have an easier time moving from a night shift to a day shift (ie, delay) than from a night shift to an afternoon shift (ie, advance) (43). Talmud Yoma clearly says, "...it is easier to postpone the hour of sleep than to rise from sleep early in the morning" (Talmud Yoma 22a). Although the Rabbis were referring to when and how to rise for the purpose of clearing the altar of ashes, in fact, these statements are in amazing agreement with what we know today about phase shifts.
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Sleep Apnea |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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...the maw [stomach] brings sleep and the nose awakens. If the awakener sleeps or the sleeper rouses (ie, if the nose induces sleep or the maw awakens), a man pines away. A Tanna taught: If both induce sleep or both awaken, a man dies forthwith (Talmud Berakoth 61b).
This is interpreted to mean several things. The rabbis are suggesting that there is some enzyme in the stomach that helps one fall asleep. One group of rabbis considers the work of the stomach to be mechanical, just grating and grinding. Another group believes that the action of the stomach is a chemical one, such that vapors from the stomach ascend and accumulate in the head, and thus, induce sleep (20). However, there is no interpretation of the "nose awakening" in the commentaries. Are they suggesting that the "nose awakens" because when people cannot breathe, they wake up, such as in the case of sleep apnea? "If the nose does not awaken, then one dies." This might also refer to sleep apnea because patients with sleep apnea who are untreated have a higher mortality rate and more often die during sleep (44, 45).
The closest reference to snoring is:
But did not Rabbi Joshua ben Levi curse anyone who slept lying on his back? In reply it was said: "To sleeping thus, if he turns over a little on his side, there is no objection, but to read the Shema [prayer] thus is forbidden even if he turns over somewhat" (Talmud Berakoth 13b).
Why did he object to having one sleep on his back? Perhaps because the person will be too noisy because he snores loudly on his back and the noise interferes with the sacred prayer.
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Nightmares |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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The existence of and treatment of nightmares can also be found in the Talmud, which states that dreams can cause distress (Berachot 55b) that will only subside if the dream is interpreted immediately (46). As explained by Askenazy and Hackett (46), these anxiety dreams, or nightmares, are divided in the Talmud into three levels of severity, each of which is treated differently. For the lightest level of nightmare, a special prayer is recited in front of the priests in the synagogue. For the middle level of nightmare, ie, one where the dreamer becomes depressed, verses from the Bible are recited in front of three people, including, "You turned my lament into dancing, you undid my sackcloth, and girded me with joy..." (Psalm 30:12). For the most severe of nightmares, one must fast on the day after the nightmare, because the dream may be a warning, and fasting, which is a form of repentance, allows one to reflect and make amends for whatever he is being warned about.
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Aging |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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But not all older people are depicted in the Bible or in the Talmud as having difficulty sleeping. When asked to what they attributed their longevity, the rabbis would reply, "nor did I ever sleep in the Beth Hamidrash [house of learning] in which one spends the day and night..." (Megillah 28a) (20). Here is an old man who does not need to nap, implying that he is sleeping sufficiently at night. This is confirmed by data from Foley et al. (49), which suggested that elderly individuals who are healthy have no complaints of sleep and no difficulty sleeping.
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CONCLUSION |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Although we think we have discovered many new features about sleep disorders, most of what we do is to match scientific data to ideas documented in the Bible and the Talmud. Our modern scientific knowledge about sleep is not new and existed even in biblical times. This wisdom is also mentioned in the Bible: "...what has been is what will be, and what has been done is what will be done; and there is nothing new under the sun." (Ecclesiastes 1:9). The conclusion for then and now is that "sleep is not tangible" (Talmud Shevu’oth 25a), that is, although the rabbis may not have fully understood sleep, they left enough clues and interpretations that agree with what science has verified thousands of years later.
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ACKNOWLEDGMENTS |
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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NOTES |
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2The Bible in this article refers to the Hebrew Bible, also known as the Tanakh. In addition to the Bible, there is the Mishnah, which is the Rabbinic text written hundreds of years later. The Mishnah consists of six major divisions. Along with the Mishnah is the Gemara, which is the Rabbis’ commentary on the laws. Together, the Mishnah and the Gemara make up the Talmud.
Received for publication November 13, 2000.
Revision received February 22, 2001.
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TOPABSTRACTINTRODUCTIONGifts of Sleep and...Stages of SleepFunction of SleepSleep DeprivationExcessive Daytime SleepinessInsomniaTreatment of InsomniaSleep HygieneCircadian RhythmsSleep ApneaNightmaresAgingCONCLUSIONNOTESACKNOWLEDGMENTSREFERENCES |
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