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 cause sleep problems include:
Other sleep problems related to the body clock
How can you treat sleep problems related to your body clock?
How you treat a sleep problem related to
your body clock depends on what is causing the problem. Here are some tips for
the most common problems.
Taking melatonin supplements may help reset your body clock. Studies
show that melatonin has reduced the symptoms of jet lag for people flying both
east and west.1
Suggestions about times
and dosages vary among researchers who have studied melatonin. Doctors
recommend that you:
The safety and effectiveness of melatonin have not been
thoroughly tested. Taking large doses of it may disrupt your sleep and make you
very tired during the day. If you have epilepsy or are taking blood thinners
such as coumadin (Warfarin), talk to your doctor before you use melatonin.
The sleeping pills eszopiclone (Lunesta) and zolpidem (Ambien) have been studied for jet lag. They may help you sleep despite jet lag if you
take them before bedtime after you arrive at your destination. Side effects include headaches, dizziness, confusion, and
feeling sick to your stomach.
For more information on jet lag, see:
If you work
the night shift or rotate shifts, you can help yourself get good sleep by
keeping your bedroom dark and quiet and by taking good care of yourself
overall. In some cases, prescription medicine or over-the-counter supplements
may help. Here are some tips on sleeping well when you do this type of shift
For more information, see the topic
Shift Work Sleep Disorder.
Some people, no matter what
they do, have trouble falling asleep at night and being up early during the
day. This may or may not cause problems for them. It depends on their lifestyle
and work or school schedule. If you are one of those night owls, there are
things you can try so that you fall asleep earlier and sleep through the
fall asleep very early and wake up before dawn may try the following to try to
stay up later at night and sleep later in the morning.
After you get
treatment for the illness or health problem that is causing your sleep problem,
you will need to practice good sleep habits. This includes getting regular
exercise (but not within 3 or 4 hours of your bedtime), going to bed at the
same time each day, and using the bed only for sleep and sex.
For more tips on improving sleep habits, see:
Health Tools help you make wise health decisions or take action to improve your health.
Herxheimer A (2008). Jet lag, search date June 2008. Online version of BMJ Clinical Evidence: http://www.clinicalevidence.com.
Other Works Consulted
Reite M, et al. (2002). Insomnia complaints. In
Concise Guide to Evaluation and Management of Sleep Disorders., 3rd ed., chap. 3. Washington, DC: American Psychiatric
December 1, 2011
Anne C. Poinier, MD - Internal Medicine
& Lisa S. Weinstock, MD - Psychiatry
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