The document discusses various topics related to sleep including sleep stages, brain waves during sleep, sleep disorders, effects of sleep on children, dreaming, and factors that influence sleep like drugs and diet. It notes that sleep involves alternating periods of REM and non-REM sleep. Non-REM sleep progresses from stages 1 to 3, then back to 2 before entering REM sleep. Brain waves measured during sleep include alpha, beta, theta, gamma and delta waves which correspond to different sleep stages. Common sleep disorders include insomnia, sleep apnea, narcolepsy and circadian rhythm disorders.

1. Samarth
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Physiology

2. Sleep is a state of reduced mental and
physical activity, in which
consciousness is altered, and sensory
activity is inhibited to a certain extent.
During sleep, there is a decrease in
muscle activity, and interactions with
the surrounding environment are
significantly reduced. While sleep is
different from wakefulness in terms of
the ability to react to stimuli, it still

3. Sleep occurs in repeating periods, in
which the body alternates between
two distinct modes: REM sleep and
non-REM sleep. Although REM
stands for “rapid eye movement”,
this mode of sleep has many other
aspects, including virtual paralysis of
the body.[citation needed] Dreams
are a succession of images, ideas,
emotions, and sensations that

4. These are vital processes that maintain
mood, memory, and cognitive function,
and play a large role in the function of
the endocrine and immune
systems.The internal circadian clock
promotes sleep daily at night. The
diverse purposes and mechanisms of
sleep are the subject of substantial
ongoing research. Sleep is a highly

5. Humans may suffer from various sleep
disorders, including dyssomnias such as
insomnia, hypersomnia, narcolepsy, and
sleep apnea; parasomnias such as
sleepwalking and rapid eye movement
sleep behavior disorder; bruxism; and
circadian rhythm sleep disorders. The use
of artificial light has substantially altered
humanity’s sleep patterns. Common
sources of artificial light include outdoor
lighting and the screens of electronic

6. The most pronounced physiological
changes in sleep occur in the brain.
The brain uses significantly less
energy during sleep than it does when
awake, especially during non-REM
sleep. In areas with reduced activity,
the brain restores its supply of
adenosine triphosphate (ATP), the
molecule used for short-term storage
Physiology

7. Sleep increases the sensory
threshold. In other words,
sleeping persons perceive
fewer stimuli, but can generally
still respond to loud noises and
other salient sensory events.
During slow-wave sleep,
humans secrete bursts of

8. Key physiological methods for
monitoring and measuring changes
during sleep include
electroencephalography (EEG) of
brain waves, electrooculography
(EOG) of eye movements, and
electromyography (EMG) of skeletal
muscle activity. Simultaneous
collection of these measurements is
called polysomnography, and can be

9. The electrical activity seen on an EEG
represents brain waves. The amplitude
of EEG waves at a particular frequency
corresponds to various points in the
sleep-wake cycle, such as being asleep,
being awake, or falling asleep.Alpha,
beta, theta, gamma, and delta waves are
all seen in the different stages of sleep.
Each waveform maintains a different
frequency and amplitude. Alpha waves
Brain Waves in
sleep

10. Beta waves take over alpha waves when a
person is at attention, as they might be
completing a task or concentrating on
something. Beta waves consist of the
highest of frequencies and the lowest of
amplitude, and occur when a person is
fully alert. Alpha and beta waves are the
only waves seen when a person is in an
awake state. Gamma waves are seen
when a person is highly focused on a task

11. Sleep is divided into two broad types: non-rapid
eye movement (non-REM or NREM) sleep and rapid
eye movement (REM) sleep. Non-REM and REM
sleep are so different that physiologists identify
them as distinct behavioral states. Non-REM sleep
occurs first and after a transitional period is called
slow-wave sleep or deep sleep. During this phase,
body temperature and heart rate fall, and the brain
uses less energy. REM sleep, also known as
Rem and non rem

12. The sleep cycle of alternate NREM and REM
sleep takes an average of 90 minutes,
occurring 4–6 times in a good night’s sleep.
The American Academy of Sleep Medicine
(AASM) divides NREM into three stages: N1,
N2, and N3, the last of which is also called
delta sleep or slow-wave sleep. The whole
period normally proceeds in the order: N1 →
N2 → N3 → N2 → REM. REM sleep occurs as
a person returns to stage 2 or 1 from a deep
sleep.There is a greater amount of deep sleep

13. Awakening can mean the end of sleep, or
simply a moment to survey the
environment and readjust body position
before falling back asleep. Sleepers
typically awaken soon after the end of a
REM phase or sometimes in the middle of
REM. Internal circadian indicators, along
with a successful reduction of
Awake
ning
Awakening

14. On a typical night of sleep, there is not
much time that is spent in the waking
state. In various sleep studies that have
been conducted using the
electroencephalography, it has been found
that females are awake for 0-1% during
their nightly sleep while males are awake
for 0-2% during that time. In adults,
wakefulness increases, especially in later
cycles. One study found 3% awake time in

15. Today, many humans wake up with an
alarm clock; however, people can also
reliably wake themselves up at a
specific time with no need for an
alarm.Many sleep quite differently on
workdays versus days off, a pattern
which can lead to chronic circadian
desynchronization. Many people
regularly look at television and other
screens before going to bed, a factor

16. Human sleep-needs vary by age and
amongst individuals; sleep is considered to
be adequate when there is no daytime
sleepiness or dysfunction. Moreover, self-
reported sleep duration is only moderately
correlated with actual sleep time as
measured by actigraphy, and those affected
with sleep state misperception may typically
report having slept only four hours despite
Ideal
duration
Ideal duration

17. Sleep difficulties are furthermore associated
with psychiatric disorders such as
depression, alcoholism, and bipolar
disorder.up to 90 percent of adults with
depression are found to have sleep
difficulties. Dysregulation detected by EEG
includes disturbances in sleep continuity,
decreased delta sleep and altered REM
patterns with regard to latency, distribution
across the night and density of eye
movements.

19. The time infants reach the age of two,
their brain size has reached 90 percent of
an adult-sized brain; a majority of this
brain growth has occurred during the
period of life with the highest rate of
sleep. The hours that children spend
asleep influence their ability to perform
on cognitive tasks. Children who sleep
Children

20. Sleep also influences language development. To
test this, researchers taught infants a faux
language and observed their recollection of the
rules for that language.Infants who slept within
four hours of learning the language could
remember the language rules better, while
infants who stayed awake longer did not recall
those rules as well. There is also a relationship
between infants’ vocabulary and sleeping:
infants who sleep longer at night at 12 months

21. Children can greatly benefit from a
structured bedtime routine. This can look
differently among families, but will generally
consist of a set of rituals such as reading a
bedtime story, a bath, brushing teeth, and
can also include a show of affection from the
parent to the child such a hug or kiss before
bed. A bedtime routine will also include a
consistent time that the child is expected to

23. During sleep, especially REM sleep, humans
tend to experience dreams. These are elusive
and mostly unpredictable first-person
experiences which seem logical and realistic
to the dreamer while they are in progress,
despite their frequently bizarre, irrational,
and/or surreal qualities that become apparent
when assessed after waking. Dreams often
seamlessly incorporate concepts, situations,
Dream
ing

24. Dreams tend to rapidly fade from memory
after waking. Some people choose to keep a
dream journal, which they believe helps them
build dream recall and facilitate the ability to
experience lucid dreams.
A lucid dream is a type of dream in which the
dreamer becomes aware that they are
dreaming while dreaming. In some
experiments, dreamers were able to

25. People have proposed many hypotheses about the
functions of dreaming. Sigmund Freud postulated that
dreams are the symbolic expression of frustrated
desires that have been relegated to the unconscious
mind, and he used dream interpretation in the form of
psychoanalysis in attempting to uncover these
desires.
Counterintuitively, penile erections during sleep are
not more frequent during sexual dreams than during
other dreams. The parasympathetic nervous system

26. John Allan Hobson and Robert McCarley
propose that dreams are caused by the
random firing of neurons in the cerebral
cortex during the REM period. Neatly, this
theory helps explain the irrationality of the
mind during REM periods, as, according to
this theory, the forebrain then creates a
story in an attempt to reconcile and make
sense of the nonsensical sensory
information presented to it. This would

27. Insomnia is a general term for difficulty falling
asleep and/or staying asleep. Insomnia is the most
common sleep problem, with many adults reporting
occasional insomnia, and 10–15% reporting a
chronic condition. Insomnia can have many different
causes, including psychological stress, a poor sleep
environment, an inconsistent sleep schedule, or
excessive mental or physical stimulation in the
hours before bedtime. Insomnia is often treated
through behavioral changes like keeping a regular
Insomnia
Insomnia

28. There is insufficient evidence to draw
detailed conclusions about the relationship
between exercise and sleep.
Nonbenzodiazepine sleeping medications
such as Ambien, Imovane, and Lunesta (also
known as “Z-drugs”), while initially believed
to be better and safer than earlier
generations of sedatives — including
benzodiazepine drugs — are now known to
be almost entirely the same as
benzodiazepines in terms of their

29. Drugs which induce sleep, known as hypnotics,
include benzodiazepines (although these interfere
with REM); Nonbenzodiazepine hypnotics such as
eszopiclone (Lunesta), zaleplon (Sonata), and
zolpidem (Ambien); antihistamines such as
diphenhydramine (Benadryl) and doxylamine;
alcohol (ethanol), (which exerts an excitatory
rebound effect later in the night and intereferes with
REM) barbiturates (which have the same problem)
melatonin (a component of the circadian clock) and
cannabis (which may also interfere with REM).
Some opioids (including morphine, codeine, heroin,
Drugs and diet

30. Some drugs may alter sleep architecture
without inhibiting or inducing sleep. Drugs
that amplify or inhibit endocrine and
immune system secretions associated with
certain sleep stages have been shown to
alter sleep architecture. The growth
hormone releasing hormone receptor
agonist MK-677 has been shown to
increase REM in older adults as well as

31. Dietary and nutritional choices may affect
sleep duration and quality. One 2016 review
indicated that a high-carbohydrate diet
promoted a shorter onset to sleep and a
longer duration of sleep than a high-fat diet.
A 2012 investigation indicated that mixed
micronutrients and macronutrients are
needed to promote quality sleep. A varied
diet containing fresh fruits and vegetables,
low saturated fat, and whole grains may be

32. Thank you