Low levels of melatonin, the hormone responsible for maintaining the body's circadian rhythm, are associated with poor sleep and depression. Our bodies may produce less melatonin as we age, which could explain why some older adults have more trouble sleeping than children do.
What You Can Do
If you struggle to get enough shut-eye, try taking .5 milligram of a melatonin supplement one to two hours before bedtime. I'd also suggest drinking melatonin-rich tart cherry juice: In a pilot 2010 study published in the Journal of Medicinal Food, subjects who drank two cups a day experienced some relief from insomnia.