💤Sleep😴

Wakefulness is a condition during which a person can have subjective experience and does voluntary work. is defined as a temporory, reversible state of physical and mental rest during which voluntary movements and subjective experience are partially or totally absent.

It is also defined as a temporory state of unconsciousness from which a person can be aroused using sensory stimulus. Wakefulness and sleep are not mutually exclusive phenomenon. But they overlap to some extent.

Types of sleep:

There are two types of sleep. 1. Slow wave sleep/  or Non REM sleep.

2. REM sleep (Rapid Eye movement) or Paradoxical sleep or Slow wave sleep:

It is the sleep a person enters into in the beginning. Duration is about 30-90 minutes at a time.

Physiological changes: 1. Decrease in metabolic rate.

2.Decrease in heart rate. Decrease in blood pressure. 

3. Decrease in rate and depth of respiration and alveolar ventilation. 

4.Decrease in sympathetic activities and increase parasympathetic

Change in the EEG pattern - more of slow waves and Delta waves

5 . Dream may be felt but not remembered.

REM sleep/Paradoxical sleep:

This type of sleep may appear in an interval of about 90 minutes. This type of sleep lasts for about 5-30 minutes at a time.

Brain metabolism increases.

movements.

Physiological changes:

1. Rapid movements of the eyeball - saccadic eye 

2. Arousal from this type of sleep is more difficult.

3. Dream is felt and remembered. HR and BP depends upon the nature of the dream.

4.EEG pattern is more similar to wakefulness condition but more deeper in sleep. This is why this type of sleep is called paradoxical sleep.

5.EEG pattern 

Functions:

1. Sleep gives physical and mental rest.

2. It helps in the relaxation of body and mind. 3. Refreshes body and mind.

4. It helps in the conservation of energy. 5. It helps to keep the person engaged.

Sleep disorders:

1. Somnambulism: (Sleep walking)- Sleep walking

with eyes open and avoid obstacles.

 2. Narcolepsy-Sudden involuntary attack of sleep during work. It is due to inability to inhibit REM sleep.

3. Insomnia-Difficulty in falling asleep and frequent awakening-due to medical and psychiatric causes.

 4. Hypersomnia-Excessively long or deep sleep from which a person can be awakened only by vigorous stimulation.- causes, head injuries, stroke,encephalitis.

5.Sleeping sickness - Suffers from insomnia during night and sleeps during day- -cause: infection by trypanosome. 

Sleep disorders affect our body very badly. It can lead us to depressions.