Final answer:
Melatonin is a hormone that regulates sleep by varying its levels in response to light exposure, increasing at night to induce sleepiness. Serotonin, which becomes melatonin in the pineal gland, is a crucial contributor to this process, and exposure to light at night can disrupt melatonin production.
Step-by-step explanation:
Melatonin is a hormone that plays a crucial role in regulating the sleep-wake cycle. Its secretion is controlled by the exposure to light: during the day, when light is perceived by the retinas, the production of melatonin is inhibited by the pineal gland, reducing drowsiness and promoting wakefulness. Conversely, as light diminishes at night, melatonin production increases, leading to induced sleepiness.
Serotonin, a precursor for melatonin, is biosynthesized from the amino acid tryptophan and affects numerous brain functions, including mood and the sleep-wake cycle. During the dark hours, serotonin is converted into melatonin in the pineal gland, further influencing sleepiness. Thus, exposure to light should be minimized during the night to avoid disrupting the synthesis of melatonin from serotonin, which can affect the sleep-wake cycle.
Triggers such as exposure to bright lights at night can hinder the production of melatonin, disrupting sleep patterns. These disruptions can be felt in the form of sleep disorders or changes in mood and are often treated with melatonin supplements to re-establish a normal sleep cycle during periods of insufficient natural production, like during winter.