APP and Alzheimer disease: A recent study demonstrates that 40 Hz (1 h/day, 30 days) light simulation ameliorates circadian rhythm disturbance in the APP/PS1 AD mouse model, restoring the hypothalamus electrophysiological changes, reducing Aβ deposition in the hypothalamus, and enhancing rhythmic expression of clock proteins, including BMAL1, CLOCK, and PER2 [22, 161].