1. Causes of Fatigue Slideshow Pictures
2. Take the Sleep Quiz
3. Foods That Help or Harm Your Sleep Slideshow Pictures

Medical Author:

Andrew Verneuil, MD

Andrew Verneuil, MD

Doctor Verneuil grew up in Orange County and played high school water polo. He attended UCLA for his undergraduate degree in Kinesiology. Doctor Verneuil graduated from Mayo Medical School. He completed six years of Internship and Residency training in head and neck surgery at UCLA. He is Board Certified with the American Board of Otolaryngology.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• What are sleep related breathing disorders?
• Why do we sleep?
• What are the stages of sleep?
• Find a local Ear, Nose, & Throat Doctor in your town
• Sleep Related Breathing Disorders Index

This is a complex topic that we only partially understand. Mammals, reptiles, birds, and even fruit flies have been observed sleeping. A manatee can sleep with one side of its brain while the other side is awake and alert. Sleeping in this way avoids a long period of unconsciousness, during which it would be very vulnerable. Humans typically need 6-8 hours of sleep every night, but individuals vary in their need for sleep. During sleep, we rest and repair our muscles and organize our thoughts and memories. Therefore, if we become sleep deprived, we feel both physically fatigued and mentally exhausted. Many studies show that sleep deprivation causes a decrease in problem solving ability, attention, and manual reflex times.

Sleep stages can be measured by monitoring the electrical impulses within the brain, often termed brain waves. These electrical impulses, or brain waves can be monitored with an electroencephalogram (EEG). Sleep can be broken up into four stages and REM (rapid eye movement) sleep. Stage 1 sleep is the most superficial and stage 4 is the deepest. Stage 1 and 2 sleep are both considered to be light sleep, while stage 3 and 4 sleep are both deeper, more restorative sleep. These stages are important for the body to feel well. REM sleep is the sleep stage in which we typically dream. During REM, the brain sends signals to the muscles to relax, so we do not "act out" our dreams. The relaxation of muscles in REM sleep can sometimes worsen sleep related breathing disorders like snoring and sleep apnea. We typically spend about 50% of our sleep in stages 1 and 2, 25% in stages 3 and 4, and 25% in REM sleep.

For additional information please visit the Sleep Center.