> One explanation may be that when the neurons shut off, they don’t require as much oxygen, so blood leaves the area. As the blood leaves, pressure in the brain

> One explanation may be that when the neurons shut off, they don’t require as much oxygen, so blood leaves the area. As the blood leaves, pressure in the brain drops, and CSF quickly flows in to maintain pressure at a safe level. If this theory about the blood leaving the brain due to the neurons needing less of it during sleep is true, then possibly that could be a supporting argument for why being more relaxed (i.e less stressed) before sleep is helpful for better sleep. My explanation for the hypothesis in the previous sentence is that the neurons due to being more worked out from being stressed would require the oxygenated blood to replenish them and thus the CSF would not naturally be able to seep in early while in bed for sleep.