After a person falls asleep, his neurons "calm down" and blood begins to leave the brain area. It makes room for cerebrospinal fluid, which "flushes" the brain with rhythmic pulsating movements.

Previous research has shown that cerebrospinal fluid and brain rhythm activity can help rid the brain of toxic proteins that accumulate in the brain as we age. With aging, these processes slow down, which can affect blood flow and reduce the pulsation of cerebrospinal fluid.

The joint work of brain waves with blood flow and cerebrospinal fluid can provide insight into various age-related disorders. Previously, it was shown that the flow of cerebrospinal fluid and brain wave activity help to "flush" toxic products from brain tissue (for example, amyloid proteins, the accumulation of which leads to neurodegeneration). What's more, as we age, the brain begins to generate fewer slow waves (normal age-related disorders), which in turn can affect blood flow in the brain and decrease the circulation of cerebrospinal fluid during sleep, leading to the accumulation of toxic proteins and memory loss. Although researchers tend to evaluate these processes separately, it now seems clear that they are very closely related.

It is currently unclear how exactly brain waves, blood flow and cerebrospinal fluid manage to coordinate so perfectly with each other. This is for further study. The authors' hypothesis is that when neurons enter the sleep state, they require less oxygen than during wakefulness. The lack of need for oxygen becomes a signal for blood to leave certain areas of the brain. As soon as the blood "has left", the pressure in the brain drops, and the cerebrospinal fluid rushes to the "vacant place" in order to maintain the pressure at a safe level. The problem is that the model doesn't fit the brain waves. What are the causal relationships of the processes? Is one of these processes dominant and the cause of the others? Or is there some hidden force that drives them all?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7971435/,kindly check this link.

https://jnnp.bmj.com/content/87/9/982,this link may be useful

https://thejournalofheadacheandpain.biomedcentral.com/articles/10.1186/s10194-018-0919-2,u can follow this link.

https://jag.journalagent.com/tjn/pdfs/TJN_23_2_43_50%5BA%5D.pdf,this link may be useful.

https://www.frontiersin.org/articles/522684,Also u can follow this link.

@Faraed Salman

Thank you too much for your answers, but links given are not opening.

@Pshkin Sergey

You are giving a very good description of relation between csf and cerebral circulation autoregulation during sleep. My self observation was that I lost my dreams because of IH, and it was regained after shunt. I hope you can also offer an explanation for spontaniety.

Many thanks

Dear Omer Elsabbagh

I understand now your question. I am familiar with a patient who also underwent bypass surgery of a cerebral vessel. He has the same problems, he is also plagued by tinnitus, painful facial bumps ... In general, such reactions are observed in the first months after the operation. However, if this does not work, consultation of a competent specialist is required, first of all, a neurosurgeon.

Regards, Sergey

Dear @Pushkin Sergey,

The important thing of your explanation of relation of csf to sleep is your clarification of the inverse relation of volume of blood to volume of csf: decrease of blood gives room to csf waves. So brain volume is constant.

The other point is the possible relation to brain degeneration.

My congratulation for your good and simple explanation.

We need in a similar explanation to find out a possible relation of csf to spontaniety.