Lecture for 2nd year medical students on 2nd March 2001 by Professor Omar Hasan Kasule Sr.
A. BIOLOGICAL CLOCK and SLEEP
DIURNAL RHYTHM and BIO RYTHM
The change or alternation of day and night is among the signs of Allah for those with insight (24:44). Several
biological phenomena are affected by the diurnal variation called bio-rythm. Examples of biorhythm are: sleep, cortisol excretion,
and melatonin excretion. Release of melatonin from the pineal is controlled by light and dark cycles. It is released in the
dark and not in light hours. Light entering the eyes stimulates the CNS that in turn stimulates the pineal gland to inhibit
SLEEP IN THE QUR'AN
Qur’anic terminology for sleep: Four terms are used by the Qur'an to refer to various forms of sleep:
nuas, sinat, and naum. The Qur'anic term nuas refers to drowsiness or dozing, a type
of sleep (3:154, ).
Nu’as is good as a preliminary to deep sleep. It is bad during salat. Salat is delayed in cases of nuas so that mistakes are not made (KS p. 315, MB #161 p 127, #162 p 127, Muslim 1718, 1719). Nuas is condemned during jumuat because of the necessity of paying full attention to the sermon(KS p. 158). The Qur'an described sinat as a minor form of sleep
(2:255). Naum is the general term for sleep. The Qur'an uses the term yaqdhat to refer to waking up from sleep or to being awake and alert ().
The ability of humans to sleep and wake up is one of the signs of Allah (30:23). It is also a blessing for humans because
their life would have been very exhausting if there were no periods of rest and sleep.
Sleep, an attribute of living things: Sleep is a human attribute. Sleep is a form of relative physical inactivity
and inattentiveness to the environment that are not compatible with divine attributes. Allah who has to look after the whole
universe and its contents does not fall asleep (2:255).
Sleep, a type of death: The Qur'an and sunnat described sleep as a type of death (6:60, 39:42. MB #2073
p 973). Some who go into sleep may never wake up again. The Prophet taught special supplications, dua, on falling asleep and on waking up in view of sleep being a major transitional event.
PHYSIOLOGY OF SLEEP:
Recurrence and reversibility: Sleep is a recurrent reversible phenomenon. Sleep is followed by wakefulness.
Wakefulness is followed by sleep.
Metabolism in sleep: Some bodily functions are diminished whereas others are increased but no functions
ever stop completely. The following are diminished in sleep: muscle inertia, basal metabolic rate, and sensory reactivity
to the environment. On the other hand mitosis and electrical activity in the brain are increased. The increased brain activity
is due to rearrangement of the database to include new information garnered during the day.
Balance and equilibrium: Sleep and wakefulness are a balance between the activation of the raphe nuclei,
the sleep system, and the ascending reticular formation, the wake system. Thus sleep and wakefulness are on a wide spectrum
depending on the relative activity of the two opposing systems of wakefulness and sleep. The reticular activation system,
RAS, is a collateral sensory pathway that is responsible for maintaining the conscious alert state.
SLEEP IS AN ACTIVE FUNCTION:
We know from studies of physiology and the evidence from the sunnat that sleep is not a passive activity.There are many intellectual and physiological processes that continue during sleep.
Some of these are even enhanced during sleep. The Prophet was described as sleeping with the eyes but not with the heart (MB
#2213 p 1028). Sleep is not an intellectually passive activity. Thinking and memory take place. Humans are not conscious of
much of this activity. Mitotic activity is highest during sleep. It is least during vigorous exercise and stress because hormones
associated with stress inhibit mitosis. Metabolism continues during sleep but at a lower rate. The Prophet forbade missing
supper, tark al asha (al tirmidhi & Ibn Majah). This is understood to mean that the body needs food energy during the
night because metabolism does not stop during sleep.
SLEEP and RESPONSIBILITY
Sleep and legal responsibility: Sleep involves a temporary suspension of full sensory perception and interaction
with the environment. A sleeping person is not legally accountable for the period during sleep (KS p. 192). If a person misses
undertaking an obligatory act because of sleep, he or she is excused under the law. In the same way deep sleep abrogates wudhu because there is no way of telling what actions the sleeping person could have
undertaken during sleep resulting in abrogation of wudhu. It is for example possible
that a sleeping person touched the genitals and thus abrogated wudhu without being
aware of it.
Times of salat and sleep: Sleep may prevent a person from performing salat
at the right time. Shaitan tries his best to prevent a sleeping person from waking
up at the time of salat (KS 49).
B. PURPOSE OF SLEEP
Sleep is a biological imperative: an adult needs 8-9 hours of sleep in a 24-hour cycle. Sleep cannot be cheated.
Long-term deprivation of sleep leads to psychological and physiological problems.
SLEEP AS REST
The human organism needs rest, raahat al jism (p 461 7:163, 7:189, 10:67,
16:6, 21:20, 25:47, 27:86, 28:72-73, 30:21, 40:61, 43:74-75, 78:9). The period of sleep is an opportunity for the human to
rest the body and the mind (78:9). This rest is both psychological (decreased anxiety and sensory stimulation) and biological
(lower respiration and circulation). During sleep there is decrease in urinary excretion, lachrymal, nasal, oral, and throat
secretions. The heart and respiratory rates are decreased. Body temperature is lowered. Pupils are constricted. Cold-blooded
animals such as reptiles and amphibians can hibernate for long periods of time during which they have a very low metabolic
rate. Sleep could be looked at as a type of hibernation but less profound than that of the frog.
SLEEP AS IBADAT:
Sleep is an act of ibadat that is opened and is closed by special supplications, dua. There is a dua before sleeping (Ibn al Qayim p. 248-9). Another
dua is recited on waking up. A special dua is recited on waking up during the night. Waking up at night for salat gives energy (Ibn al Qayim p. 253) for the next day's work.
SLEEP AS REORGANIZATION OF BRAIN ARCHITECTURE
Memory storage is restructured during sleep as new facts garnered during the day are sorted out, correlated with
old information and is stored.
SLEEP and METABOLIC READJUSTMENT
Homeostatic adjustments are easier to carry out during sleep because there are no concurrent new changes.
C. NORMAL SLEEP
EEG PATTERNS OF SLEEP
Electrophysiological studies have enabled us to understand many phenomena related to sleep. Using the electro-encephalogram
(EEG), 3 patterns of sleep have been identified according to the pattern of electrical waves recorded: alpha, beta, theta,
and delta sleep patterns.
TYPES, STAGES, AND CYCLES OF SLEEP:
There are 2 types of sleep, REM and non-REM. In REM sleep there is rapid eye movement and intense electrical activity
in the brain. Non-REM sleep is electrically more quiescent. There is cyclic alternation between REM and non-REM sleep. Different
events and mental experiences occur in REM and non-REM sleep. There are 5 stages of sleeping. There is a gradation in depth
of sleep from stage 1 to stage 5, stage 1 being the lightest and stage 5 the deepest sleep. Stages 1-4 are in REM sleep is
REM. Stage 5 is non-REM.
ETIQUETTE OF SLEEPING:
The Prophet taught sleeping on the right side of the body (MB# 2074 p 973, Ibn al Qayim p. 247.He forbade sleeping on the face (Ibn al Qayim p. 248-9). It is recommended to sleep with wudhu. Medical
research will uncover the physiological basis for these prophetic recommendations. It is forbidden to sleep naked because
one may be surprised and wake up exposing nakedness, awrat.
AMOUNT OF SLEEP
A human should take the adequate amount of sleep appropriate to the age and physiological condition. More sleep
than this is offensive. Waking up for ibadat at night has special merit.
TIME OF SLEEP
Most sleep should be at night. The prophet recommended siesta, qailuulat, a period of sleep and rest in
OCCURRENCE OF DREAMS:
All people dream in both REM and non-REM sleep. Dreams during REM are forgotten. It is only dreams in non-REM sleep
that are remembered. Remembering of dreams is not perfect. Dreaming during daytime, popularly known as daydreaming, is possible.
It may occur during sleep or without deep sleep. The Prophet (PBUH) is reported to have dreamt in his sleep during the day
(MB# 2181 p 1015-6).
NATURE OF DREAMS:
Dreams may be review of actual daytime activities. Thus people dream about persons, objects, and events that are
of immediate concern to them. There is considerable distortion of the reality. Because of the highly developed faculty of
the human mind to be imaginative and creative, some dreams may be very sophisticated and it may prove difficult to relate
them to the daily activities or concerns of an individual. Dreams also have a tendency to fantasy. Incidents in dreams last
as long as they would in normal life. In general contents of dreams even if well remembered cannot be taken to be true facts
on which action can be based.
GOOD and BAD DREAMS
The Qur'an described dreaming during sleep, ru'uyat manamiyat (p. 516-517
8:43, 12:4-6, 12:36, 12:43-44, 12:100, 21:5, 37:102, 37:105, 48:27, 52:32). Similarly many hadiths have been related about
dreams and dreaming(KS p. 254-256). Good dreams are from Allah (MB #2177 p 1014)
and should be told. It is an offense to lie when reporting a dream. The offense may be a simple exaggeration or changing the
content of a dream from bad to good or vice versa. Because of memory distortion and forgetting that occurs, a dreamer may
not be able to piece together a coherent story and may be inclined to confabulate in order to cover up for memory defects.
This is strictly forbidden. It would rather be better not to report the dream at all. Bad frightening dreams are from shaitan
(KS 50, Muslim #5613, 5616, 5618, 5619, 5620, 5621, 5623, 5627, 5629, 5632). Bad dreams should not be reported (Muslim # 5639,
5640, 5641, 5642).
DREAMS OF PROPHETS AND RIGHTEOUS PEOPLE:
Dreams of prophets are always true and are part of revelation, wahy (MB
#2176). Prophet Ibrahim did not
hesitate to carry out Allah’s command when he dreamed about slaughtering his son Ismail (KS 47). The dreams of prophet Yusuf turned out to be true (p. 1356 12:4-5). The Prophet Muhammad dreamt about hudaybiyat
and followed the dream. There is a hadith that seeing the Prophet in a dream is
true because shaitan does not come in his similitude (Muslim #5635, 5636, 5637, 5638). Dreams of righteous people are a type
of prophethood (MB#2176 p 1014, MB #2178 p 1014, MB#2182 p 1016). We however can never tell for certain who is a righteous
person in contemporary times because as humans we judge from outside appearances and only Allah knows what is inside humans.
INTERPRETATION OF DREAMS:
The Qur'an described the interpretation of dreams, ta'awil al ru'uyat (p
221 12:6, , -37, -49, 12:100-101). Only dreams of prophets can be interpreted correctly. Only prophets
can interpret people's dreams correctly. Prophet Yusuf interpreted dreams very effectively (p. 1355 12:6, 12:21, 12:36, 12:4,
12:44-49, 12:100-101). The Prophet Muhammad interpreted many dreams. Interpretation of dreams of ordinary humans who are not
prophets by non-prophets should be discouraged.
E. SLEEP DISTURBANCES
Insomnia is a symptom for other illnesses. The prophet described the body as one entity such that if any part of
it is affected all of it is affected by insomnia. Insomnia is due to activation of the reticular system by pain or emotional
factors. This causes activation of the limbic system.
Waking up in the middle of the night (MB# 2075 P 974) does occur. Somnambulism is dangerous because a person can
harm himself and others.
BED-WETTING (NOCTURNAL ENURESIS):
Bedwetting is normal in children and abnormal in adults. It stops with age as neurological and bladder functions
mature. It may have a genetic basis.
NARCOLEPSY (IRRESISTABLE URGE TO SLEEP):
Narcolepsy is an irresistible urge to sleep. It may be part of certain disease syndromes. It could interfere with
performance of salat.
SHAITAN and SLEEP
Shaitan can tie
knots on the head of a person to make it difficult to wake up (MB 604, KS p. 49). It can also urinate in the ears to prevent
waking up (KS p. 49, MB# 605). This is part of shaitan’s strategy to prevent humans from remembering Allah.