The overall increased risk of death from long-term sleep deprivation that is not compensated is well known. A new study sheds light on mortality in relation to a shortened REM phase – the part of sleep characterized by rapid eye movements.
We spend around a quarter of our sleep each night in so-called REM sleep. REM stands for «Rapid Eye Movements», i.e. rapid movements of the eyes with closed lids. Unlike in the deep sleep phase (called non-REM sleep), from which we are particularly difficult to wake up, our brain works at full speed during REM sleep: It stores new knowledge, processes experiences of the day – and tends to react more sensitively to waking stimuli . In addition, we dream particularly intensively in this phase.
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Relationship between shortened REM (dream) phase and death rate
For a study published in the medical journal Jama Neurology, the sleep patterns of a total of 4,050 people were analyzed. Sleep researcher Eileen B. Leary, a graduate student at the Stanford Center for Sleep Science, showed that over a 12-year period, the death rate was 13 percent higher when the REM sleep deficit was just 5 percent. This is independent of gender, age and other variables such as general health. With a sleep duration of seven to eight hours, we are in REM sleep for about two hours. A minus of five percent corresponds to just six minutes.
With an average sleep duration of seven to eight hours, we are in REM sleep for about two hours. Frequency and extent increase towards the end of the night. In this example, five percent less REM sleep would correspond to just six minutes.
The researchers’ statements were based on data from two patient groups: 2,675 men (mean age 76 years) who participated in a study of sleep disorders at multiple US sites between 2003 and 2016, and a clinical sleep study in women and men who had attended the study since 1988 at the University of Wisconsin. Every four years, the effects of sleep disorders, in particular sleep apnea (breaks in breathing at night), are examined there.
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The male group had a 13 percent increased risk of dying from cardiovascular or other non-cancer diseases over a 12-year period for every 5 percent reduction in REM sleep. The Wisconsin study reflected this finding, although it included younger study participants.
shortcomings of the study
Now one has to say: The observations do not inevitably mean that the one causes the other. A REM disorder does not necessarily lead to earlier death. As further shortcomings of the study, sleep specialist Dr. University of South California’s Rai Dasgupta told CNN: There was no control group. And: Many of the participants received antidepressants. These are known to affect REM sleep.
«Among the various theories about the function of REM sleep are that it helps form new memories, stimulates the central nervous system and balances brain chemistry,» the assistant professor of clinical medicine tells the broadcaster.
REM disorder often precedes Parkinson’s disease
Previous studies have shown that disturbances in the REM phase – more specifically, a shortened REM duration – often lead to memory deficits. It is also known that this particular disorder often precedes Parkinson’s disease. Observational studies have shown that 70 to 80 percent of older people with such a sleep disorder will develop Parkinson’s disease over the next 10 to 15 years. (FITBOOK reported).
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But it is not only the lack or the lack of sleep in its individual phases that can seriously damage health. Research from Harvard University in March 2020 also showed that irregular sleep – specifically changing bedtime by more than 1.5 hours – can damage the heart and double the likelihood of a heart attack or stroke on average.