Question

question 1
what makes people tired at night but helps people stay awake during the day?
the time of day you eat
the amount of water you drink
circadian rhythm
the brain

Explanation:

Circadian rhythm is the internal biological clock that regulates the sleep - wake cycle. It makes people feel tired at night (when it's time to sleep) and helps them stay awake during the day. The time of day one eats and the amount of water one drinks do not directly regulate the fundamental sleep - wake cycle in the way circadian rhythm does. While the brain is involved in many functions including sleep regulation, the specific term for the internal mechanism that drives the daily sleep - wake pattern is circadian rhythm.

Answer:

Circadian Rhythm