Health Conditions

What causes it?

There are many elements about the mechanisms of sleep and wakefulness that scientists do not understand. What is known is that sleep is primarily controlled by two systems in the brain: one that induces sleep, and sleep-related processes, and one that regulates sleep within a 24-hour cycle. This cycle, which corresponds to periods of light and darkness, is known as the circadian rhythm cycle. Researchers are discovering that this cycle a process controlled by genes that are found in living creatures ranging from the lowly fruit fly to human beings.

Researchers know that as human beings we go through a variety of stages that can be measured by brain wave patterns. This includes a stage in which our eyes move rapidly, where it is assumed we are dreaming. This stage of sleep is therefore known as rapid eye movement (REM) sleep. Sleep disorders result from either internal abnormalities or external disturbances to these cycles. The feeling of having had enough sleep, or sleep satiety, is related to whether one has gone through all of the cycles of sleep, including both dreamless and REM sleep. We cycle through these stages multiple times per night.

The ongoing study of sleep disorders spans many medical fields, including neuroscience, genetics, physiology and psychology. Some of the mechanisms that play a role in sleep disorders are the subject of study at The National Center for Sleep Disorders Research. This center is situated within the National Heart, Lung, and Blood Institute - part of the National Institutes of Health (NIH) in Bethesda, Maryland. Research includes the study of the genes that play a role in narcolepsy (a condition characterized by brief attacks of deep sleep), how sleep disturbances affect the immune system, and the role of sleep/wake cycles in triggering heart attacks.