Health: Sleep

3. the fatigue that people experience after changing time zones during travel.
6. a class of sleep disorders in which a person is partially, but not completely, aroused from sleep.
10. a condition in which a person grinds or clenches his or her teeth while sleeping.
11. A shortage of sleep that leads to tiredness and other health problems.
12. an amino acid that aids the body in producing chemicals that cause sleep.
14. a type of therapy in which a machine is used to open the airways during sleep; a treatment for sleep apnea.
15. a disorder that causes people to have difficulty regulating their sleep.
16. a potentially serious disorder in which a person actually stops breathing for short periods of time during sleep.
17. a disorder in which people experience prickling, tingling, or other irresistible urges to move their legs.

1. a group of nerve cells in a part of the brain called the hypothalamus.
2. a part of the brain that regulates appetite and energy consumption.
4. people who can function well on less sleep than others.
5. are naturally occurring physical, behavioral, and mental changes in the body that typically follow the 24-hour cycle of the sun.
7. a substance that increases the body's activity and makes it more difficult to sleep.
8. a hormone released by the pineal gland that increases feelings of relaxation and tiredness.
9. a type of cell that makes up the body's nerve tissues.
13. a condition in which the body is unable to fall asleep or stay asleep.