What is the body clock? body's "biological clock," or 24-hour
cycle (circadian rhythm), can be affected by light or darkness,
which can make the body think it is time to sleep or wake up.
The 24-hour body clock controls functions How are body clock
problems and sleep problems connected? Body clock sleep problems
have been linked to a hormone called melatonin. Light and dark
affect how the body makes melatonin. Most melatonin is made at
night. During the day, light tells your body to make less
melatonin. If you work at night in artificial light, your body
may be making less melatonin than it needs. as those who can't
sleep until very late and those who go to bed very early—have
circadian (say "ser-KAY-dee-un") rhythms that are different from
those of most people. Other people with sleep problems may have
regular circadian rhythms but have to adjust them to new
situations, such as working a What sleep problems are related to
problems with your body clock? Things that may affect melatonin
production and can caus