Good Sleep Depends on Efficiency, Not Just Duration

Sleep quantity and quality are both key to better mental and physical health

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Good sleep is so essential to physical and mental wellness it’s considered one of three pillars of health, along with physical activity and good diet. But most people aren’t getting the duration or quality of sleep they need, a new study suggests, in part because their time in bed — supposedly conked out and sleeping soundly — is not efficient.

The study, published today in the Journal of the American Heart Association, also found that people who sleep too little tend to have erratic sleep schedules and are more apt to suffer poor heart health. That adds to past research showing that good sleep is one of the best ways to keep the mind sharp and emotions settled, increase daytime focus and productivity, and ensure good physical health and a long life.

However, exactly how much sleep each person needs, and even data on how much people actually get, are both surprisingly unclear. The new findings add a significant twist to the latter measure.

The study employed wrist-worn activity trackers to measure seven days of activity and sleep duration of 1,920 U.S. adults ages 45 to 84, with the average age at 69. In addition, the participants answered sleep questionnaires and spent one night hooked up to a machine that detects key measures of sleep quality, including brain waves, oxygen levels, heart rate and breathing rate.

A whopping 63% of the study participants were found to sleep less than seven hours per night — the oft-recommended minimum threshold for good health — and 30 percent slept less than six hours, the researchers report. That’s a dramatically different take on sleep duration compared to existing U.S. federal data, which states that 32.5% of U.S. adults get less than seven hours a night.

Why the big difference?

I asked the study’s lead author, Nour Makarem, PhD, to explain the discrepancy. She cited two reasons:

• The federal data relies on self-reporting by individuals, which is known to be prone to error, whereas her team’s study included objective measures of sleep duration.