Sleep

Sleep

Definition
*It is regular, recurrent, easily reversible state that is characterized by relative quiescence and by a great increase of the threshold of response to external stimuli to the waking state
*polysomnogram finding of sleep:-
Sleep is made of two physiological state:
1.Non rapid eye movement sleep (NREM) which composed of
-stage 1 which represent 5%
-stage II which represent 45%
-stage III which represent 12%
-stage IV which represent 13%
TOTAL &NREM 75%
2.Rapid eye movement sleep (REM) which represent 25%
*SLEEP PATTERN
About 90 minute after sleep onset NREM yields to the first REM episode of the night which last for about 10 min. then it continues as sleep progress to reach about 30 min. during the last third of the night.
*SLEEP REGULATION
It is function & number of interconnecting systems or center that are located chiefly in the brainstem and that mutually activate and inhibit one another. Many study support the role of serotonin in sleep regulation, decrease serotonin will reduce sleep for considerable time.
Nor epinephrine firing cause marked reduction in REM and increase in wakefulness
-Brain acetylcholine in increase REM.
-Dopamine lead to wakefulness
Function of sleep
1.Restorative function.
2.homeostatic function for normal thermoregulation and energy conservation.
3.Satisfying metabolic needs of the starvation and exercise
*SLEEP REQUIREMENTS
-some people are normally short sleepers who require fewer than 8 hours for sleep each night.
-longer sleepers are those who sleep more than 9 hours each night which have more REM and more REM density(duration of each REM)
Sleep wake Rhythm
Without external clues, the natural body clock follows a 25 hr cycle .the influence of external factors such as light-dark cycle, daily routines, meal periods entrain people to the 24-hr clock, sleep is also influenced by biological rhythms.


SLEEP DISORDERS

Sleep is essential for social and mental wellbeing .knowledge is uncomplete. Researches & sleep laboratories have been established to study sleep disorders

RAPID EYE MOVEMENT 25%

Starts after >90 min. of sleep that is characterized by
1.decrease in muscle tone
2.increase in HR
3.increase in RR
4.periodic increase in BP
5.increased O2 consumption
6.penile erection
7.poikilothermic
If the person awakes suddenly the dream will repeate 1.5 hr interval
NON RAPID EYE MOVEMENT SLEEP 75%
-initial entry into sleep