Why Sleep Consistency May Be More Important Than Duration

by Staff Writer
November 15, 2023 at 11:05 AM UTC

Study highlights how sleep regularity, more than duration, significantly influences mortality risks from various health conditions.

Could one weird trick be the secret to healthy sleep? According to a new paper in the journal, Sleep – yes. 

Prioritizing Consistency

The prospective cohort study found that regular sleep patterns are more crucial to health and longevity than spending  eight hours in bed. Using UK Biobank data from over 60,000 participants, the study’s authors defined sleep regularity as day-to-day consistency in sleep-wake timing. Participants in the top 20 percent for sleep regularity had a lower all-cause mortality risk than those in the bottom 20 percent who reported the most erratic slumber patterns.

Risk reduction was significant, ranging from 20 percent to 48 percent across four distinct measures:

  • Sleep Onset Regularity: Did participants generally maintain a reliable bedtime?
  • Sleep Offset Regularity: Did participants have a predictable wake-up time?
  • Sleep Midpoint Regularity: This measure calculated the consistency of the midpoint between nodding off and opening the eyes. In other words, did participants have a regular halfway point between when they fall asleep and when they wake up?
  • Sleep Duration Regularity: Did participants maintain a dependably stable duration of sleep? The term was defined by the total amount of time the individual actually spent asleep during a specific period, typically measured in hours and minutes.

Mortality and Sleep Factors

Additionally, the study looked at the question of cause-specific mortality. Here again, consistency seemed to trump duration. A reliable pattern of rest was the more important factor in predicting the risk of death from heart and metabolic diseases, cancer, and other causes. People in the top 40 percent of sleep regularity had a lower risk of dying from these causes compared to the bottom 20 percent. An analysis showed risk reductions of about 57 percent for heart diseases, 39 percent for cancer, and 61 percent for other causes. Even after adjusting for confounding factors, these reductions remained significant.

“Sleep regularity may be a simple, effective target for improving general health and survival,” the authors concluded.

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Rethinking Slumber Rules

One finding undercut the popular belief that an eight hour snooze is the most essential health habit. Researchers found no significant association between sleep duration and the chances of early death after adjusting for regularity. In other words, a regular six hours of shuteye a night was a better indicator of health than an erratic eight hours schedule.

However, the researchers still maintain that it’s still important to spend plenty of time in repose. Investigations that included both self-reported and measures linked dozing too much or too little to poorer health outcomes, including increased mortality risk. The sweet spot of 7-9 hours in dreamland has been confirmed by numerous and robust studies measuring actual sleep times, the authors noted. They emphasized that prioritizing both quantity and regularity is critical for optimal well-being and longevity.

New Rest Recommendations

The National Sleep Foundation recently acknowledged the importance of sleep consistency in a consensus statement that included new guidelines emphasizing its health benefits. 

“The Consensus Panel concluded that consistent timing of bedtimes and wake times are associated with improved outcomes across multiple dimensions of health and performance—including alertness, cardiovascular and metabolic health, inflammation and mental health,” said a statement put out by panel chair and senior author, Charles A. Czeisler, MD, division chief of sleep and circadian disorders at  Brigham and Women’s Hospital and Frank Baldino, Jr., Ph.D. Professor of Sleep Medicine at Harvard Medical School.

The authors of this new study offered some advice for cultivating sensible bedtime habits. Consider establishing a consistent routine by turning off the lights and setting the alarm clock at the same time every day, even on weekends. Create a relaxation-friendly environment, including a comfortable mattress and a calm, dark, and quiet bedroom. Individuals who can’t seem to get in the groove should consult with a healthcare professional. 

“Our results confirm an important role for sleep duration in predicting mortality, but reveal that sleep regularity is an even stronger predictor,” the authors wrote. “Fortunately, sleep regularity may also be an easier dimension to target through interventions.”

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