Sleep Deprivation can cause a decline in Brain Volume:

According to a University of Oxford study researchers said, “Sleep repairs and restores the brain.” They surveyed 147 adults, aged between 20 and 84 years, about sleep habits to determine the relationship between sleep difficulties and brain volume. The survey pertained to sleep duration, how long it took subjects to fall asleep, and the use of sleeping medications. All participants also underwent two brain scans.

 Researchers found that sleep difficulties caused a rapid decline in brain volume in frontal, temporal and parietal areas. The impact was higher in participants above the age of 60.

Author Claire E. Sexton, in a press release stated, "It is not yet known whether poor sleep quality is a cause or consequence of changes in brain structure, There are effective treatments for sleep problems, so future research needs to test whether improving people's quality of sleep could slow the rate of brain volume loss." If that is the case, improving people's sleep habits could be an important way to improve brain health."