TORONTO — The baby’s cries wake you up at 2 a.m. The dog knocks over the trash can. And by six in the morning, the birds are chirping and the sunrise seeps into your bedroom.
By the time your alarm sets off, you feel more exhausted in the morning than when you went to bed the night before. Israeli researchers, in a study they say is the first of its kind, suggest that interrupted sleep is just as bad for your body as no sleep at all.
Those little disturbances that wake you up — even for minutes at a time — affect your thinking, attention span and your mood the next day, according to scientists from Tel Aviv University’s School of Psychological Sciences.
Interrupted sleep is equivalent to no more than four consecutive hours of sleep, they suggest. And the research is especially applicable to parents nursing babies.
“The sleep of many parents is often disrupted by external sources, such as a crying baby demanding care during the night. Doctors on call, who may receive several phone calls a night, also experience disruptions,” Dr. Avi Sadeh said in a university statement.
“These night wakings could be relatively short…but they disrupt the natural sleep rhythm.”
Sadeh directs a sleep clinic at the university. There, he was advising parents, exhausted and restless, when he decided to study the potential link between waking up at night and being in a bad mood by day.
But the study’s based on student volunteers — their sleep patterns were monitored at home using wrist devices that logged when they were sleeping and awake. Students had a normal eight-hour rest cycle, then encountered nights when they were woken up four times by phone calls. They had to complete a quick computer task before going back to sleep after 10 minutes of being awake. The next day, unsurprisingly, those students weren’t happy campers.
But their alertness had also waned on computer tests compared to a full night’s rest even after only one night of interruptions.
“Our study shows the impact of only one disrupted night,” said Prof. Sadeh. “But we know that these effects accumulate and therefore the functional price new parents — who awaken three to ten times a night for months on end — pay for common infant sleep disturbance is enormous.”