Poor REM Sleep, Higher Risk for Depression?
Preliminary study suggests that emotional stress builds when this phase is disturbed, creating a 'vicious cycle'
By Alan Mozes
MONDAY, Feb. 8, 2016 (HealthDay News) -- REM (rapid eye movement) sleep is the phase when dreams are made, and a lack of good REM sleep has long been associated with chronic insomnia.
But new research is building on that association, suggesting that the bad and "restless" REM sleep experienced by insomnia patients may, in turn, undermine their ability to overcome emotional distress, raising their risk for chronic depression or anxiety.
"Previous studies have pointed to REM sleep as the most likely candidate involved in the regulation of emotions," said study lead author Rick Wassing. He is a doctoral candidate in the Department of Sleep and Cognition at the Netherlands Institute for Neuroscience in Amsterdam.
Wassing noted, for example, that while REM is underway, key arousal hormones such as serotonin, adrenaline and dopamine are inactive. This, he added, may indicate that it is during good REM sleep when the emotional impact of memories is properly processed and resolved.
But when REM sleep is disturbed, emotional distress may accumulate. And Wassing said current findings indicate that over time this accumulation eventually leads to a "vicious cycle" of overarousal, during which insomnia promotes distress, which promotes arousal, which promotes ongoing insomnia.
Wassing and his colleagues discuss their findings in the early issue of PNAS, published Feb. 8.
According to the U.S. National Institute of Neurological Disorders and Stroke, sleep involves five distinct phases, which broadly track from light sleep to deep sleep to REM sleep. This cycle then repeats itself several times throughout the night.
The last phase, REM, is characterized by rapid and shallow breathing, rapid eye movement, and a rise in heart rate and blood pressure. It also gives rise to dreams. Experts believe that REM sleep triggers brain centers that are critical to learning, and may be vital to healthy brain development in children.
To explore the importance of good REM sleep to emotional regulation, the Dutch investigators conducted a two-part study.
The first involved completion of a questionnaire by nearly 1,200 respondents (average age of 52) who were enrolled in the Netherlands Sleep Registry. All were asked to self-report the severity of their insomnia, as well as their emotional distress, arousal and/or troubling nighttime thoughts.