Melatonin is a hormone that is naturally released in your brain. This is a major component of your body’s natural circadian rhythm, which regulates sleep and wake cycles. Some scientists argue that these substances are responsible for the decrease in metabolism that takes place before falling asleep. While melatonin is released, the body temperature and blood flow to the brain decreases, and our muscles slowly lose the tension and slack.
As people age, their bodies begin to produce melatonin levels are lower, when that happens, the ability to fall asleep – and stay asleep – can be inhibited. This is why it’s not unusual at all for people who are middle-aged and older have a sleep problem.