A new study, led by researchers from Stanford University, has uncovered an association between total REM sleep quantity and lifespan. The study is the first to investigate the specific relationship between REM sleep and mortality.
The last few years have seen an explosion of new research examining the importance of sleep in maintaining optimum health. While irregular overall sleep durations have been linked to a number of negative heath outcomes, including increased mortality risk, this new study set out to focus specifically on REM sleep.
The research examined data from two independent longitudinal studies, comprising over 4,000 subjects who were followed for up to 20 years. Overall, the research found less time spent in REM sleep significantly correlated with increased mortality. In fact, every five-percent reduction in average REM sleep was associated with a 13-percent increase in the risk of early death.
"In our busy, fast-paced lives, sleep can feel like a time-consuming nuisance,” says senior author Eileen Leary to HealthDay. “This study found in two independent cohorts that lower levels of REM sleep was associated with higher rates of mortality. The function of REM is still not well understood, but knowing that less REM is linked to higher mortality rates adds a piece to the puzzle.”
The study of course offers no insight into potential causal relationships between REM sleep duration and mortality, and the researchers are clear in noting the association may not be causal. Instead, they say, disrupted REM sleep could be a sign of other factors that negatively effect overall mortality.
An editorial accompanying the release of the new study, from a trio of neurologists not affiliated with the research, suggests this association may not be causal but it does imply REM sleep quantity could be an effective general health biomarker. The editorial also points out more research will be necessary to investigate this link, as there are medications that are known to disrupt the cyclical pattern of different sleep stages (known as "sleep architecture"), and REM quality.
“Neurologists should also consider the possible effects of medications, particularly antidepressants, on sleep architecture,” the editorial says. “Serotonin reuptake inhibitors, selective serotonin and norepinephrine reuptake inhibitors, and tricyclic antidepressants all push REM sleep to later in the night (increased REM sleep latency) and reduce time in REM sleep. Should we monitor REM sleep in patients on these medications or factor this effect into decision-making when devising a treatment plan? These remain unanswered questions.”
Healthy adults are thought to spend between 20 and 25 percent of their total sleep time in REM phases. Leary and her colleagues suggest those adults spending less than 15 percent of total sleep in REM phases are most at risk of early death. So, although less REM sleep may not directly be causing early death it could be a clear clinical sign something is wrong.
The new study was published in the journal JAMA Neurology.
