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, also known as N-acetyl-5-methoxy tryptamine, is a hormone that is produced by the pineal gland in animals and regulates sleep and wakefulness. Melatonin is also produced in plants where it functions as a first line of defense against oxidative stress. In animals, melatonin is involved in the entrainment (synchronization) of the circadian rhythms including sleep-wake timing, blood pressure regulation, seasonal reproduction, and many others.