MAPT and insomnia: In AD, the impaired cholinergic pathway alters the sleep-wake cycle with insomnia at night and excess sleep in the day, OR-A increases Aβ42, P-Tau levels in the Cerebro Spinal Fluid (CSF) causes rapid eye movement sleep, orexinergic neurons in the hypothalamus degenerate, and cognitive function deteriorates [120]–[122].