Ever since Vogel's studies in the 1970s it has been known that acute sleep deprivation, particularly deprivation of REM sleep, produces a positive effect on people with depression. The extremely depressed person feels much better if he goes without REM sleep for a night or two. The suicidally depressed patient may forget the idea of suicide for a few hours or days if he is deprived of REM for a night or two. These basic observations have been confirmed many times since the 1970s (see the reading list below) but the question as to how REM deprivation helps depression has been left unanswered.
Despite the dramatic beneficial effects on serious depression we still have no idea as to why REM deprivation alleviates, at least temporarily, major depression. This is a very surprising fact. You would think that any clue or lead on what kinds of treatment work for major depression would be followed up on with major pushes in the research arena backed up by major funding streams from the National Institutes of Health. But the voices of depressed people, apparently, are not as loud as the voices of other health-related interest groups so funding for depression studies has never been adequate to the scale fo the problem.
A recent study, however, has managed to throw some fascinating light on the relations between acute sleep deprivation and alleviation of depression.
Gujar N, Yoo SS, Hu P, and Walker MP. of the Sleep and Neuroimaging Laboratory, Department of Psychology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California have recently reported (Gujar et al., Sleep deprivation amplifies reactivity of brain reward networks, biasing the appraisal of positive emotional experiences. J Neurosci. 2011 Mar 23;31(12):4466-74) that sleep deprivation amplifies reactivity throughout human mesolimbic reward brain networks in response to pleasure-evoking stimuli. In addition, this amplified reactivity was associated with a biased increase in the number of emotional stimuli judged as pleasant in the sleep-deprived group. Interestingly the degree of bias toward labeling incoming stimuli ‘positive' when in the sleep deprived state was correlated with activity in mesolimbic regions. In short, it appears that acute sleep deprivation increases reactivity in reward networks of the brain. The older neurobiological literature on REM deprivation in animals suggested that motivational and drive related states were heightened during after REM deprivation as animals seemed much more attuned to reinforcing and pleasureable stimuli. These facts led the older researchers to suggest that the normal function of REM was to dampen down pleasureable or motivational states or that REM functioned to re-tune catecholaminergic synapses throughout the brain. In any case both the older literature and the newer data suggest that REM specializes in handling negative motivational and appetitive states and thus it should not be surprising that REM deprivation has a potent if temporary anti-depressant effect. Nor should it be surprizing that REM indices are virtually always elevated in major depression. It seems that major depression is fueled at least in part by a kind of dis-inhibition of REM physiology.
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