sleep stages neural machanism theories cycle of sleep disorder

1. Sumbitted By – Ankita manwani

2. Sleep is split into two main categories:
Rapid Eye Movement (REM) sleep, and
non-Rapid Eye Movement (NREM) sleep
The American Academy of Sleep Medicine (AASM) further
divides NREM or N into 4 stages :

4. Stage – 1 (NREM sleep – N1)
Brain waves become small and irregular with varying frequencies.
The transition of the brain from alpha waves having a frequency of 8–13 Hz (common in the
awake state) to theta waves having a frequency of 4–7 Hz. •
This stage is sometimes referred to as somnolence or drowsy sleep.
 Some people may also experience hypnagogic hallucinations during this stage. •
 It lasts for 10 min and accounts for 5% of total sleep time

6.  In NREM sleep – N2 is characterized by sleep
spindles ranging from 11–16 Hz and K-complexes.
 During this stage, muscular activity as measured by
EMG decreases, and conscious awareness of
the external environment disappears.
 This stage occupies 45–55% of total sleep
in adults.

8. NREM 3 OR N3 NREM 4 OR N4
 2-4 Hz sleep wave
 Dreaming starts
0.5 – 2 Hz sleep wave
Night terrors/sleep
walking/bedwetting/ sleep
talking
It accounts 4-6% of
sleep
 It accounts for 12- 15% of
sleep

9. REM SLEEP STAGE
 This type of sleep is also called paradoxical sleep because it is a paradox that a person
can still be asleep despite marked activity in the brain.
 A type of sleep in which the brain is quite active. However, the brain activity is not
channeled in the proper direction for the person to be fully aware of his or her
surroundings, and therefore the person is truly asleep.
 Rapid eye movement, It accounts for 20–25% of total sleep time in most human adults. •
 . Most memorable dreaming occurs in this stage
 The electroencephalogram (EEG) shows a pattern of brain waves similar to those that
occur during wakefulness.

10. Thankyou

11. NEURAL
MECHANISM
OF SLEEP and
WAKING
Submitted by Asna Saidi

12. NEURAL MECHANISM OF SLEEP and
WAKING
•It includes ;
• CEREBRALCORTEX
• HYPOTHALMUS
• RETICULARACTIVATING SYSTEM (RAS)/
RETICULAR FORMATION
• THALAMUS
• BREMERS’S CERVEAU ISOLE PREPARATION
(Isolated forebrain preparation)

13. Cerebral
cortex
Cerebral cortex is responsible for monophasic sleep or wakefulness
of choice.
A monophasic sleep pattern is when an individual sleeps once per
day, typically for 8 or so hours a night whileA polyphasic
sleep pattern is when a person sleeps for periods of time throughout
the day.
Thus humans need cerebral cortex for development of monophasic
sleep or wakefulness of choice.
Dogs have a sleep pattern like humans, they are monophasic.
Puppies like human baby are polyphasic

14. HYPOTHALMUS
Hypothalamus is responsible for
polyphasic sleep and
wakefulness.
Abnormal tendencies to sleep
can be caused byTumors and
inflammations in hypothalamic
region.
An experiment is conducted on
monkey- in which a lesion is
performed on the posterior
hypothalamus by RANSON.
Result of the experiments -
Monkeys with such lesion
showed profound somnolence
and slept continuously for 4-8
days after operation.
They showed marked drowsiness
even after waking up for several
months.
When the same lesion is
performed on the anterior
hypothalamus in rats.
Results in On recovery from
operations they carried out all
normal activities effectively but
never slept properly .They
developed problems of fatigue
and went into coma and
ultimately died.
Stimulation of hypothalamus
produced conflicting results. On
one hand it induced sleep but on
the other hand it caused activity
and excitement

15. RETICULAR ACTIVATING SYSTEM (RAS)/
RETICULAR FORMATION
• RAS is primary waking center.
• RF is a network of nuclei and its pathways begin in the hindbrain and
extend till midbrain.
• Its electric stimulation caused arousal and activation of cortical EEG.
• Lesions in reticular formation caused signs of somnolence.Thus RAS is
the principle waking center of the brain.
• An experiment conducted by Moruzzi and Morgan reveals that
electrically stimulated RF and found that stimulation of it led to cortical
arousal and alertness.
• They also found that disruption of it produced a low level of alertness
and large wave synchronized EEG recordings characteristics of sleep.

16. THALAMUS
There is a group of nuclei which
project into cerebral cortex.
It is called thalamic extension of
the reticular formation but it has
certain projections different from
RAS so it is seperatlley called
DiffuseThalamic Projection
System (DTPS).
Electrical stimulation of DTPS
gives rise to recruiting response
(Increase in size of cortical
response) in several areas of the
cortex.
High frequency stimulation of
DTPS gave rise-To cortical
arousal response but lowering
frequency of electrical
stimulation - It had the opposite
effect and induced sleep.
When the DTPS was destroyed,
stimulation of RAS caused a
cortical arousal response.

17. BREMERS’S
CERVEAU
ISOLE
PREPARATION
(Isolated
forebrain
preparation)
• Bremers on the basis of his “sensory stimulation
hypothesis” of sleeping and waking concluded that sleep
is produced by the lack of sensory of sensory input to
the cerebral cortex, with wakefulness resulting from
sensory stimulation.
• He achieved this by conducting an experiment in which
he made a cut between the inferior and superior colliculi
depriving the higher brain areas of the sensory
information arriving through the spinal cord and
brainstem structure.
• This results in that those cats had undergone this
operation slept continuously but over a long term period
showed desynchronized EEG.

18. BRAIN AREAS
RESPONSIBLE FOR
REM SLEEP
Submitted by Sargam
Bhatnagar

19. BRAIN AREAS
RESPONSIBLE
FOR REM
SLEEP
GIGENTOCELLULARTEMENTUM FIELD (FTG)
• They are a group of nerve cells in Pons near locus
coeruleus.
• They increase their firing rate during REM Sleep.

20. LOCUS
COERULUS
• Locus coeruleus is important for cortical arousal and
behavioral alertness and also for REM sleep.
• Destruction of this structure produced increased sleep
and decreased wakefulness.
• Inactivation of anterior portion of locus coeruleus was
found to induce sleep and stimulation invariably
produced wakefulness.
• In addition its activity is highly correlated with levels of
wakefulness in monkey: the greater the activity, the
higher the level of behavioral activity.
• Similar study showed the firing rate of locus coeruleus
neurons increases as an animal wakens and declines
when it goes to sleep.

21. PGOWAVES
• PGO waves are brief phasic
burst of electrical activity
that originate in pons and
propogates to lateral
geniculate nuclei and then to
primary visual cortex.
• When electrodes were put in
LGN the
• EEG became desynchronized
and mascular activity ceased
leading to REM sleep.

22. ACETYLCHOLINERGIC
AGONISTS
Acetylcholinergic agonists
facilitate REM sleep in the
peribrachial area.These neurons
initiate
PGO waves and cortical arousal
through their connection with the
thalamus.

23. PERIBRACHIAL NEURONS
They are present in the bottom of brain stem and
also induce REM sleep through their connection
with motor neuron in tectum.
REM sleep also begins when activity of nor
adrenergic and seretonergic neuron ceases.

24. BRAIN AREAS RESPONSIBLE FOR NREM SLEEP
RAPHE NUCLEI
In pons they control SWS sleep.
When it was lesioned SWS reduced
to 15%.
VENTROLATERAL PREOPTIC AREA
(VLPA)
It is group of GABAergic neuron in the preoptic
area and their activity suppresses alertness and .
behavioral arousal and promotes Sleep

25. Submitted by:-
KavyaTyagi

27. Insomnia disorder
• Insomnia, known as sleeplessness. It is sleep disorder where people have trouble
sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia
is typically followed by daytime sleepiness, low energy, irritability, and a
depressed mood. Insomnia can be short term, lasting for days or weeks, or long term, lasting
more than a month.

28. Types of insomnia
Insomnia can classified into :
Transient Acute Chronic

30. Sleep related
breathing disorder
Sleep disordered breathing is associated with change in the brain,
include amyloid dispositions In brain regions typically involved in
alzheimers disease.
• SLEEP APNEA:
• Characterized by pauses in breathing or periods of shallow
breathing during sleep
• Each pause can last for a few seconds to several minutes and they
happen many times a
• night
• There may be a choking or snorting sound as breathing resumes.
As it disrupts normal
• sleep, those affected are often sleepy or tired during the day
• Breathing is interrupted by a blockage of airflow or breathing
stops due to a lack of effort
• to breathe.

33. Centraldisorderof
hypersomnalence
• The central disorders of hypersomnolence are characterized by severe daytime
sleepiness, which is present despite normal quality and timing of nocturnal sleep.
• NARCOLEPSY
It is characterized by periods of excessive daytime sleepiness that usually last from
seconds to
minutes and may occur at any time. It occurs because of lack of brain chemical
“Hypocretin” and
immune system dysfunction. People may involuntarily fall asleep during normal activities.
People also experience episodes of sudden loss of muscle strength, known as cataplexy
(episodic
loss of muscle function, slight weakness such as limpness at the neck or knees or inability
to speak
clearly, to a complete body collapse)

35. Circadian rhythm sleep wake cycle
• DELAYED SLEEP –WAKE PHASE DISORDER
A disorder in which a person's sleep is delayed by 2 or more hours beyond the socially acceptable
or conventional bedtime. This delay in falling asleep causes difficulty in waking up at the desired
time.
• ADVANCED SLEEP -- WAKE PHASE DISORDER
Characterized by early evening bedtimes (approximately 8-9pm) and early morning awakenings
(approximately 4-5am).
In circadian rhythm disorders, endogenous sleep-wake rhythms (body clock) and the external
light-darkness cycle become misaligned.

36. • IRREGULAR SLEEP – WAKE RHYTHM
People with these disorders have sleep times that seem to be out
of alignment. Their sleep
patterns do not follow the “normal” sleep times at night.
• SHIFT WORK DISORDER
Characterized by insomnia and excessive sleepiness affecting
people whose work hours overlap
with the typical sleep period.
• JET LAG DISORDER
It is a temporary sleep problem that can affect anyone who
quickly travels across multiple time
Zone.

38. PARASOMNIA
BY GARIMA
RATHORE

39. WHAT IS PARASOMNIA?
Parasomnias are types of disturbing
disorders that can happen just before
you fall asleep, while you’re sleeping,
or as you’re waking up.
It can be divided on basis:
1. NREM related
2. REM related

40. Sleep walking
Sleep terrors/night terrors
NREM related
(non rapid eye
movement)

41. SLEEP WALKING
• It is known as somnambulism or noctambulism. It is a phenomenon of
combined sleep and wakefulness.
• Sleepwalking occurs during slow wave sleep stage in a state of low
conscious and perform activities that are usually performed during a state of
full consciousness.
• Eg; walking to a bathroom, or hazardous as cooking, driving.
• It may last as little as 30 seconds or as long as 30 minutes.
• Sleep walking is when you’re moving around and look awake but are
actually asleep.

42. Sleep terrors/night terrors
• Night terrors are similar to nightmares but usually happen during deep sleep.
• Episodes of screaming, intense fear and flailing while still asleep
• Usually occur in children (4-12yrs)
• May occur because of stress, hypothyroidism, fever, and sleep apnea
• A sleep terror episode usually lasts from seconds to a few minutes (10-30min), but
they may last longer.
• Night terrors tend to happen during periods of arousal from delta sleep, also known
as slow- wave sleep.

43. Nightmare
Rem sleep behaviour disorder
REM RELATED
(rapid eye
movement)

44. nightmare
• Also called a bad dream, is an unpleasant dream that can
cause a strong emotional response from the mind, typically
fear but also despair, anxiety and great sadness.
• Occur in children (3-6yrs) and ocassionally in adults.
• Dreams are never recalled.
• Sufferers often awaken in a state of distress and may be
unable to return to sleep for a small period.

45. Rem sleep
behaviour
disorder
• RBD occurs when you act out vivid dreams as you sleep.
These dreams are often filled with action.They may be
violent. Episodes tend to get worse over time. Early
episodes may involve mild activity. Later episodes can
be more violent.
• RBD episodes occur during rapid- eye movement(REM)
sleep. Normal sleep consists of a series of REM dream
episodes.They occur about every 1 ½ to 2 hours each
night.
• E.G – grabbing, punching, klcking

46. Other parasomnias
1. SLEEP ENURESIS
• Involves involuntary urination while asleep after the age at which bladder control
usually occurs.
2. CONFUSIONALAROUSAL
• usually happen when you wake from a deep sleep during sleep the first part of the
night.
• Also known s excessive sleep inertia or sleep drunkenness, makes you very slow when
you wake up.
3. NOCTURNAL LEG CRAMPS
• Sudden, uncontrolled muscle contractions during rest.
• Cramping feeling may last from a few seconds to 10 minutes, but the pain may linger.

48. THEORIES OF SLEEP
BY: AKANKSHA
SHARMA(M.Sc)

49. (1)REPAIR AND RESTORATION THEORY OF
SLEEP
• This theory suggests that NREM
sleep is important for restoring
physiological functions, while
REM sleep is essential in
restoring mental functions.
• The body restores itself during
sleep.
• Repair and restoration theory
allows the brain to perform
"housekeeping" duties.

50. to flush out
waste
toxins.
Proper
functioning of
body
revitalizing and
restoring the
physiological
and mental
functions
removal of
potentially
neurotoxic
waste products
Healthy
mind and
body
IMPORTANCE
cell division
and tissue
synthesis
Release of
growth
hormones

51. (2) EVOLUTIONARY THEORY OF SLEEP
• Also known as the adaptive theory of sleep,
suggests that periods of activity and inactivity
evolved as a means of conserving energy.
• According to this theory, all species have
adapted to sleep during periods of time when
wakefulness would be the most hazardous.
• Evolutionary explanations suggest 4
possibilities:
A.FORAGING REQUIREMENTS
B.PREDATORAVOIDANCE
C.ENERGY CONSERVATION
D.WASTE OFTIME

52. A.FORAGING
REQUIREMENTS
• Sleep is a necessity but the
time spent in sleeping is
constrained by food
requirements.
• Herbivores eat plants that are
relatively poor in nutrients and
thus need to spend a great deal
of time eating and
consequently have less time for
sleeping.
• Carnivores eat food high in
nutrients and so do not need to
eat continuously and can thus
afford to rest much of the time
helping them conserve energy.
A.PREDATOR
AVOIDANCE
• Meddis proposed this theory and
suggest that sleep helps animal
stay out of the way of predators
during the parts of the day when
they are most vulnerable.
• Sleep is constrained by predator
risk. If an animal is a predator
then it can afford to sleep for
longer whereas prey species
have less time to sleep due to
risk of being killed.
• Siegal concurs with this view
suggesting an animal is more at
risk when awake and likely to be
injured as sleep enables both
energy conservation and
avoiding dangers.
ENERGY
CONSERVATION
• Humans need to expend
a great deal of energy in
maintaining body
temperatures.
• All activities use energy
and animals with high
metabolic rates require
more energy.
• Therefore sleep provides
a period of inactivity to
conserve energy.
WASTE OFTIME
• Sleep has no vital
function and it actually
interferes with the man’s
function

53. (3) INFORMATION CONSOLIDATION
THEORY OF SLEEP
The information consolidation theory of sleep is based on cognitive research
and suggests that people sleep in order to process information that has been
acquired during the day.
Support for this idea stems from a number of sleep deprivation studies
demonstrating that a lack of sleep has a serious impact on the ability to recall
and remember information.

55. (4) PROGRAMMING- REPROGRAMMING
THEORY
This theory holds that unimportant information is "erased" and important
information is locked into more permanent memory.
Recent research indicates that REM sleep may be the key in reinforcing learning.
Babies and children experience a larger portion of REM sleep than adults, and
adults who are in school or undergoing intense intellectual training increase their
amount of REM sleep.
When people are deprived of REM sleep their creativity and problem solving
processes are affected.

56. (5)HABITUATION THEORY
In 1960, Sokolove and Rogers gave this Habituation
Theory.
The basis of this theory is normal habituation.
It states that habituation leads to boredom and which in
turn leads to loss of arousal and finally sleep.

58. SUBMITTED
BY: JYOTI
YADAV

60. Functions of sleep
• Function of sleep is to eliminate behavioral
responsiveness during spare time when the organism
is not well adapted.
• Restoration and recovery of body systems.
• Sleep helps to preserve the rest phase of the sleep-
inactivity cycle.
• Sleep is essential for learning and memory. there will
be information transfer between cerebral cortex and
hippocampus during sleep.
• Sleep improves neurobehavioral and neurocognitive
performance.
• Sleep helps to avoid exhaustion, and sleep functions
for the recovery of the nervous system from synaptic
use.
• Sleep has a major role in the recovery from neuronal
plasticity associated with learning and memory.

61. • The function of REM sleep is to “activate,
select, instruct or release important motor
activity”.
• Neuronal activities that occur during REM
sleep reinforces psychological
individuation.
• REM sleep occurs predominantly in infancy
hence most of the neurologic development
happens in the that age. Presence of REM
sleep in adulthood suggests REM sleep are
related networks are also necessary to
maintain the behaviors at a mature level.
• Activity dependent neuronal maturation
occurs during REM sleep.
• Sleep is a recovery and recuperative
process.
• SWS functions for general body restitution
and REM sleep functions as brain “repair”.

62. • Sleep favors anabolism.
• “The function of REM is to remove certain undesirable
modes of interaction in the network of cells in the
cerebral cortex.”
• REM sleep regulation function is emphasized.
• REM sleep is necessary for unlearning or reverse
learning of unwanted behaviors by removing
“parasitic” modes of neuronal interconnections.
• REM sleep erases unnecessary memory.