DIFFICULTY FALLING OR STAYING ASLEEP: PSYCHIATRIC DIMS – SLEEP DISTURBANCE AND DEPRESSION
Virtually all depressed people experience sleep disturbance, particularly early-morning awakenings. As a rule the more severe the sleep disorder, the more serious the case of depression, at least as measured on standard psychiatric tests. Generally the depressed sleep less than normal individuals. However, about 15 to 20 percent of depressed people, including adolescents, may sleep more. In severe cases the victim obtains less total sleep and experiences more periods of wakefulness during the night than nondepressed people.
A great deal of research is currently being conducted to study the effects of depression on sleep cycles as detected through EEG tracings. For example, we know now that depressed patients show considerably more Stage 1 (light) sleep but less Stages 3-4 (deep) sleep than normal people. In some specific types of depression there is a shorter period of time, technically known as latency, between the onset of sleep and the first REM period. This reduced REM latency seems to be connected with other symptoms of depression, including loss of appetite, dulled mood, and the absence of pleasurable feelings. The depressive’s first REM period is usually long and active, while in normal people the busiest REM period occurs at the end of the night. Depressed people also have more REM episodes. I should point out, however, that it is possible to exhibit the sleep disturbances associated with depression without actually developing other symptoms of the illness. Similarly, impaired sleep continuity and loss of slow-wave sleep are common to many psychiatric disorders, including anxiety, obsessive-compulsive behavior, schizophrenia, and alcoholism.
These sleep abnormalities persist even beyond the period during which a depressed individual experiences symptoms. Eventually, it is thought, the EEG may help physicians refine their diagnosis of depressed patients to differentiate between some of the more subtle forms of the disorder as well as the other psychiatric conditions just noted. Approximately 90 percent of depres-sives show some form of EEG-verified sleep disturbance. Some experts believe that such clues as REM latency can be used to diagnose past or predict future occurrence of depression in certain patient types.
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