Native Americans served in World War I even though they were not citizens of the United States. In fact, it was not until after World War II in the 1965 passage of the Voting Rights Act that all states were required to allow Native Americans to vote on the same basis as any other American.
Overview. Melatonin is a hormone secreted by the pineal gland in the brain. It helps regulate other hormones and maintains the body's circadian rhythm. The circadian rhythm is an internal 24-hour clock that plays a critical role in when we fall asleep and when we wake up. When it is dark, your body produces more melatonin.
Melatonin â A signal of darkness and marker for circadian rhythms Melatonin is a naturally occurring hormone that is key to sleep and the sleep-wake cycle in humans and animals 8. In the body, melatonin is produced by the pineal gland in the brain when night falls. The retina detects failing light, and the level of melatonin gradually increases, reaching its peak in the middle of the night in natural circumstances 9.