Question

the pineal gland produces the hormone ____, which is involved in our daily sleep - wake cycle. fill in the blank

Explanation:

The pineal gland is known to secrete melatonin. Melatonin plays a crucial role in regulating the sleep - wake cycle (circadian rhythm). As light decreases (especially in the evening), the pineal gland increases melatonin production, which signals the body to prepare for sleep.

Answer:

melatonin