SLEEP AND AWAKE SYSTEM

Why do we get sleepy or how do we stay awake? To answer these questions we need to look up on hypothalamus which is sleep and awake center. There are multiple different nucleus inside the hypothalamus. Two main nuclei is called as tuberomammilary nucleus and ventrolateral preoptic nucleus.

To start with, tuberomammilary nucleus is a histaminergic nucleus and it is responsible for arousal as it increases the cortical activation and projections to acetylcholinergic neurons by increasing the release of acetylcholine in the cerebral cortex. 

Ventrolateral preoptic nucleus (VLPO) works as a GABAergic nucleus which inhibits the neurons of the reticular activating system that are involved in the wakefullness. Its dysfunciton may cause multiple disorders like insomnia and narcolepsy.

Narcolepsy is neurologic disorder which is related with the loss of the brains activity in the sleep and awake system . Its a execessive daytime sleepiness which may observed with another symptom, cataplexy which is a sudden episodic muscle weakness . 

There are three main subsystems; Orexin projections from the hypothalamus ,reticular activating system and ventrolateral preoptic nucleus., These systems are all associated with impairments due to a greatly reduced number of hypothalamic orexin projection neurons and significantly fewer orexin neuropeptides in cerebrospinal fluid and neural tissue, compared to non-narcoleptics.

VLPO is functionally active during sleep period primarily in non-REM stage. There are different rhymtms for the REM and non REM stages. First we observe the alpha rhtym which is seen in the resting period after that it changes to beta rhytm that is seen in the REM period where we dream and so on..

 As a non REM stage disorder, periodic limb movement may have seen which is a repetitive cramping or jerking of the legs.It is the only movement disorder that occurs only during sleep. Another loss of function in the brain during non REM stage may cause Sommanbulism which is known as sleep walking. It is mainly observed at young ages.

As mentioned before VLPO may cause insomnia as it releases the inhibitory neurotransmitter GABA which inhibits the reticular activating system. In this kind of loss of brain activity can be treated with many drugs like ; Benzodiazepines (GABAergic drug), Alprozolam (5HT antagonist). There are many different kind of drugs like antihistaminic and antidepressants that can be used for sleeping problems. 

Keep in mind that we are all under the placebo effect ..

NAZLI SERIN