It turns out that much of the difference in sleep patterns can be pinned down to circadian rhythms and hormones. According to the National Institute of General Medical Sciences, circadian rhythm refers to the changes that happen to your mind and body over a 24 hour cycle. Your energy levels and sleep patterns will be affected by your circadian rhythm. This is because your circadian rhythm can influence the release of the hormone melatonin that makes you tired.
The Sleep Foundation notes that circadian rhythm is latest during adolescence and then gradually progresses earlier from there. A person’s circadian rhythm shifts by half an hour per ten years starting in middle-age. One reason for this is that as they age, their bodies produce less melatonin. This causes them to get up earlier in morning.
The reason for this could also be because older people’s eyes are less able to receive as much light. This plays an important role in maintaining a healthy circadian rhythm. The Sleep Foundation suggests that people over 60 who have trouble with their sleep patterns should get more daylight during the day and at night.