Final answer:
Increased melatonin production makes people sleepy when the sun goes down. Darkness triggers melatonin production, which aids in sleep, while light decreases its production, promoting wakefulness. Maintaining darkness at night helps sustain healthy melatonin levels and sleep cycles.
Step-by-step explanation:
People get more sleepy when the sun goes down due to increased melatonin production. Melatonin is a hormone that regulates the sleep-wake cycle, and its secretion is influenced by the light-dark cycle of the environment. Exposure to light inhibits the production of melatonin, whereas darkness stimulates its production. Melatonin release is stimulated by darkness and inhibited by light, causing higher levels of melatonin in the blood during the night, which promotes drowsiness. Conversely, during the day, when there is more light, melatonin production decreases, helping individuals stay awake.
It's important to avoid exposure to bright artificial light during the night, as it may suppress melatonin production and disrupt the sleep cycle. Circadian rhythms, including sleep patterns, are regulated by melatonin, which is produced by the pineal gland in the brain.