Question

Name the hormone which maintains the sleep-wake cycle.

Answer 1

Hint: The sleep-wake cycle is an important part of the circadian rhythm of the body. It is regulated by a hormone that is produced by the pineal gland in the brain. The secretion of this hormone increases during the night or in low-light environments and decreases during the day or in well-lit surroundings.

Complete answer:
• The hormone that maintains the sleep-wake cycle is melatonin.
• The sleep-wake cycle forms an important component of the circadian rhythm of our body. The circadian rhythm is a cycle that regulates our body clock throughout the day. This cycle can get influenced by multiple factors, one of which is light.
• When less light falls on the cells of the retina (the photosensitive layer of the eye), it signals the brain to release the hormone melatonin, thereby increasing its levels in the bloodstream. It is released from the pineal gland. When the light in the surroundings increases, the levels of melatonin decreases and this causes us to wake up.
• Besides sleep, melatonin influences various factors. It causes loss of heat, reduces arousal, and delays the secretion of cortisol (a hormone that increases blood sugar and blood pressure). All this is done to prepare the body for sleep.
• This is how a sleep-wake cycle is regulated.

Note: Since melatonin plays an important role in the sleep cycle as well as the quality of sleep, people who suffer from sleeping disorders are given melatonin supplements. This is because sleeping disorders may arise due to a decrease in levels of melatonin.
Melatonin supplements are even effective for people experiencing jet lag.