After a fitful night’s sleep — maybe you were woken up by your newborn or 2am texts or garbage trucks outside your window — you might tell yourself it’s ok, you’ll make up for “lost sleep” on the weekend.
In fact, if you’re concerned about your mood or ability to pay attention the next day, a night of sleep with repeated wakings may be just as bad as no sleep at all.
There have been many experiments that have shown the negative effects of sleep restriction, or what most people refer to as sleep deprivation. Those generally look at what happens when people get too few hours of total sleep.
But much less is known about interrupted sleep, or “night wakings,” when a person is woken up for 5-10 minutes. “The impact of such night wakings on an individual’s daytime alertness, mood, and cognitive abilities had never been studied,” said psychologist Avi Sadeh, a coauthor of the study, in a statement. He became interested in night wakings after interacting with many parents of newborn babies at the sleep clinic he directs at Tel Aviv University.
While most sleep experiments are performed in a laboratory setting, Sadeh and his team conducted this study in a home-based setting, meaning that participants were allowed to sleep in their own beds.
The 61 test subjects, ranging in age from 20-29 years old, kept sleep diaries and tracked their sleep patterns using “actigraphy,” a wristwratch-like device that records the wearer’s movements and tracks sleep-wake patterns.
All participants slept a normal eight-hour night. Then half of them were subjected to “restricted sleep,” meaning no more than four hours, and the other half spent eight hours in bed, but were woken up four times for 10-15 minutes at a time. A computer test measured their sustained attention, or ability to engage with a task, and survey questions determined their moods.
What They Found
After just one night of frequent interruptions, participants were cranky with shorter attention spans. They reported depression, fatigue and negative moods.
The basic conclusion? Interrupted sleep is equivalent to no more than four hours of consecutive sleep. But good luck telling that to a crying newborn.
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