New Clues About Why Sleep Loss Is Linked To Depression, Anxiety
#Depression and #sleep problems are intimately connected, as many people know, and the relationship seems to go both ways. Sleep disturbances, of various types, are central symptoms of depression; on the other hand, chronic lack of sleep seems to predispose one to developing depression.
It was the latter connection that the authors of a new study in the Journal of Behavior Therapy and Experimental Psychiatry wanted to look into, exploring a phenomenon called repetitive negative thinking (RNT), a hallmark of both mood and anxiety disorders.
The phenomenon RNT is a relatively new term, which the authors of the new study from Binghamton University define as “abstract, perseverative, negative focus on one’s problems and experiences that is difficult to control.” This sounds a lot like intrusive thoughts or rumination, which many of us are familiar with. The difference in the “flavor” of RNT in someone with depression vs. anxiety might be that in depression negative thinking involves thoughts about the past, and in anxiety, thoughts about the future.
To study the link between this kind of negative thinking and sleep, the team tried to recruit participants who had experienced intrusive thoughts or sleep issues. They had them come into the lab and view negative images (guns, knives, threatening animals), positive images (nature, sports) or neutral ones (household items). The team measured their attention with eye-tracking technology, which is more accurate than asking the person to recall or even understand their response.
It turned out that people who got less sleep—either because they slept fewer hours throughout the night or had trouble falling asleep—had trouble not attending to the negative images. In fact, people who slept fewer hours looked at the negative images longer and had more trouble disengaging from them. This wasn’t true for the positive or neutral images. All of this suggests a link between sleep loss and the inability to suppress negative stimuli, which again is a key element of mood and anxiety disorders.
“We found that people in this study have some tendencies to have thoughts get stuck in their heads, and their elevated negative thinking makes it difficult for them to disengage with the negative stimuli that we exposed them to,” said study author Meredith Coles in a news release. “While other people may be able to receive negative information and move on, the participants had trouble ignoring it.”
It’s not totally clear why people had trouble ignoring the negative images—whether it’s something that happens subconsciously or consciously. But in either case, a lack of sleep may deteriorate the neural processes that normally suppress or shed negative thoughts and negative incoming information.
“[The connection] may be explained by a reduction in available cognitive resources, particularly those needed to inhibit information and handle novel information,” the authors write in their paper. “It is possible that sleep disruption deals a ‘second hit’ to attention control in individuals who are already vulnerable in their subjective and/or physiological responses to negative information.”
The study builds nicely on growing literature in this area. Research from the University of Pittsburgh last month, for instance, found that when teens were deprived of sleep, areas of the brain involved in reward were less active—and the teens reported more symptoms of depression. The authors of that study suggest that lack of sleep in adolescence may predispose teens to both depression and addiction later on. Earlier work has looked at the links between depression and a dysregulated biological “clock,” or circadian rhythm.
More work will need to be done to understand all the connections between sleep and mood, anxiety and even addiction. In the meantime, making sleep a priority rather than an indulgence is key. Experts have been saying that for a long time, and research is showing just how true it is—not only for the brain, but for our mental health.
Alice G. Walton , Contributor I cover health, medicine, psychology and neuroscience. Opinions expressed by Forbes Contributors are their own.
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