Stages Of Sleep

REM intrusion during inappropriate periods

Normal  aging  is  not  associated  with  decreased intelligence. Decreased rapid   eye   movement (REM) sleep, adiminished sense of taste and smell, increased sleep latency and thinning of the vaginal mucosa are associated with normal ageing.

Sleepwalking disorder is a parasomnia associated with slow wave sleep. The patient is usually difficult to awaken, amnesic for the episode. Common in children, sleepwalking peaks between ages 4 and 8 years and usually disappear by adolescence. The severity of the disorder range from less than one episode per month without any problem to several episodes complicated by physical injury to the patient and others.

Brain is very active but muscles are virtually paralyzed

REF: Check APPENDIX-11 for “Sleep physiology”

Repeat from June 2010

Bruxism REF: GUYTON & HALL, Ganong, various internet resources. See APPENDIX-11 for “SLEEP PHYSIOLOGY”

Normal sleep involves two states: REM sleep and non-REM sleep. REM sleep is often associated with dreaming.

Non-REM sleep is a period of decreased physiologic and psychological activity and is further divided into stages 1, 2, 3, and 4 on the basis of visually scored EEG patterns.

Night terror (pavor nocturnes), occurs primarily in young children during the first several hours after sleep onset, in slow-wave sleep (NREM stage 3, 4 sleep).

In this, the child suddenly screams exhibiting autonomic arousal with sweating, tachycardia, and hyperventilation.

It is difficult to arouse children and they rarely recalls the episode on awakening in the morning. 

Ref: Porth Pathophysiology: Concepts of Altered Health States By Ruth A. Hannon, Pages 585-6 ; Lexicon of Psychiatry, Neurology, and The Neurosciences By Frank J. Ayd, Page 931

• Stage 1 sleep is characterised by the presence of theta waves 4-Hz).
• In stage 3 of NREM sleep, a high-amplitude delta rhythm (0.5–4 Hz) are seen.
• Stage 4 of NREM sleep is characterised by the presence of slow waves.

Stage 2 has more theta waves than stage 1 and is associated with sleep spindles (short bursts of 12-16 Hz activity) and K-complexes (high amplitude slow waves with superposed sleep spindles) on the electroencephalogram.

Based on EEG, EMG, EOG characteristics, REM sleep can be divided into two stages, tonic and phasic. Characteristics of the tonic stage include a desynchronized EEG, atonia of skeletal muscle groups, and suppression of monosynaptic and polysynaptic reflexes. Phasic REM sleep is characterized by rapid eye movements in all directions as well as transient swings in blood pressure, heart rate changes, irregular respiration, tongue movements, and myoclonic twitching of chin and limb muscles.

Acetylcholine is the neurotransmitter of primary importance for the induction of REM sleep. Some of the other neurotransmitters do function in sleep, but REM sleep can occur in their absence.

During REM sleep, the brain is highly active and responsive, but the body is virtually paralyzed because of active inhibition of skeletal muscles by dedicated population of neurons in the brainstem. During REM sleep, the high amplitude slow waves seen in the EEG during sleep are periodically replaced by rapid, low voltage, EEG activity, which resembles that seen in the awake aroused state and in stage 1 sleep.  Another characteristic feature of REM sleep is the occurrence of pontogeniculo-occipital spikes.

This is a straight forward memory question. There are two kinds of sleep: rapid eye movement (REM) sleep and non-REM (NREM), or slow-wave sleep.

Ref: Ganong’s Review of Medical Physiology 23rd edition, Chapter 15.

A. i.e. Hypnagogic hallucinations

D i.e. EEG shows decreased activity

B i.e. Stage II

B i.e. Sleep walking

B i.e. Delirium

B i.e. Beta

A i.e. Deep sleep

C i.e. Referred to as paradoxical sleep

D i.e. Low amplitude, mixed frequency wave

A i.e. REM sleep

D i.e. Delta activity

Ans. is `a’ i.e., 5% iodine & 10% KI

Ans. A: REM

Humans aroused at a time when they show the EEG characteristics of REM sleep generally report that they were dreaming, whereas individuals awakened from slow-wave sleep/ NREM do not. This observation and other evidence indicate that REM sleep and dreaming are closely associated. The tooth-grinding (bruxism) that occurs in some individuals is also associated with dreaming.

Ans. D: Seen in REM sleep

Ans. D i.e. Night terrors

Sleep

• Alpha waves: Eyes closed and mind wandering
• Night terrors are seen in: NREM sleep
• Sleep walking/ somnabulism is seen in: NREM sleep (stage 3/4)
• Sleep terror/pavor nocturnus:

— Seen in NREM sleep (stage 3/4)

— Treated by diazepam

Ans. Catalepsy

Ans. Grinding of teeth during sleep

Ans. is ‘c’ i.e., REM sleep

REM sleep decreases the secretion of GH. Other three stimuli increase GH secretion.

Ans:B.)NREM sleep.

In the image,Wave A -represents awake stage,Wave B-represents REM sleep,Wave C-represents NREM sleep.

Sleep Cycle.

• Sleep is generally divided into 2 broad types: nonrapid eye movement (NREM) sleep and REM sleep.
• NREM and REM occur in alternating cycles, each lasting approximately 90-100 minutes, with a total of 4-6 cycles. In general, in the healthy young adult NREM sleep accounts for 75-90% of sleep time (3-5% stage I, 50-60% stage II, and 10-20% stages III and IV). REM sleep accounts for 10-25% of sleep time.
• Based on EEG changes, NREM is divided further into 4 stages (stage I, stage II, stage III, stage IV).
  Stage I sleep is also referred to as drowsiness or presleep and is the first or earliest stage of sleep.

  • The earliest indication of transition from wakefulness to stage I sleep (drowsiness) usually consists of a combination of drop out of alpha activity and slow rolling eye movements.
  • Stage II is the predominant sleep stage during a normal night’s sleep. The distinct and principal EEG criterion to establish stage II sleep is the appearance of sleep spindles or K complexes.
  • Stages III and IV sleep are usually grouped together as “slow wave sleep” or “delta sleep.
• The different types and stages of sleep can be best identified using polysomnography, which simultaneously measures several body functions such as brain wave activity (electroencephalogram or EEG), eye movement (electrooculogram or EOG), muscle activity (electromyogram or EMG), respiration, heart rhythm, etc.
• Electroencephalogram :
  • Non-REM sleep is characterized by very slow but relatively high amplitude or high voltage oscillations (with the frequency gradually slowing and the amplitude increasing as sleep deepens), while REM sleep shows a much faster and lower amplitude trace, much more similar to normal waking activity
  • Brain waves during non-REM sleep tend to be highly synchronized, and those during REM sleep much more unsynchronized.
• Electrooculogram (EOG) :
  • Rapid eye movements during REM sleep, and little or no eye movement during non-REM sleep.
• Electromyogram (EMG) :
  • The body is effectively completely paralyzed during REM sleep, the body does make some limited movements during non-REM sleep, including a major change in body position about once every twenty or thirty minutes on average.

Ans. d. Quiet wakefulness

Ans. is ‘b’ i.e., Delta wave

Stages of Sleep

• Sleep is basically divided into two phases : ‑
• Non-REM (NREM) or slow-wave sleep : – It is called Non-REM sleep because no rapid eye movement (REM) is there on eletrooculogram, rather there is slow or quiscent eye movement. It is also referred as S-sleep (synchronized sleep) or quiet sleep or orthodox sleep because there diminished physiological functions and a low level of overall activity. It is further divided into : ‑

1. Stage 1 : – It is a transition from wakefulness to sleep and is characterized by disappearance of alpha activity and appearance of theta activity. There is slow eye movements.
2. Stage 2 : – It is characterized by typical EEG activity i.e., Sleep spindles and IC-complex’. No eye movement occurs.
3. Stage 3 & 4 : – Stage 3 & 4 are stages of deep sleep. These are also called slow wave sleep as these stages are characterized by slow delta waves. Delta wave appearance starts in stage 3 and dominated in stage 4.

• REM sleep : – The REM sleep is so named as there is rapid roving movements of eye, i.e., rapid eye movement (REM)on electro-oculogram. It is also called paradoxical sleep because there is a paradoxical elevation of brain activity & metabolism and physiological activity. The high-amplitude slow waves seen in stage 3,4 of REM sleep is replaced by rapid low voltage activity (beta wave). Features of REM sleep are : –

1. EEG Beta wave, Reappearance of alpha wave, Saw-tooth wave (low voltage fast activity), Ponto­genital-occipital spikes.
2. Dreaming
3. Other features : – Generalized muscular atony, Penile erection, autonomic hyperactivity (Increased pulse rate & BP) and intermittent movement of small muscle groups.

Ans. is ‘b’ i.e., NREM stage 3, 4

• Slow wave sleep (stage 3 & 4 of NREM sleep) disorders :- Sleep walking (somnambulism), night terror (sleep terror or pavornocturnus), Nocturnal enuresis, Bruxism (teeth grinding), and sleep talking (somniloquy).
• REM sleep events/disorder :- Nightmares, nocturnal penile tumescence, Narcolepsy.