Even if you’re in bed for eight hours, waking up every two or three hours and sleeping through the night are two very different things, says a new study from Tel Aviv University.
In fact, the study's authors determined that a full night of interrupted sleep is equivalent to no more than four hours of consecutive sleep, in terms of how you'll likely feel and act the next day. To find that out, researchers allowed student volunteers to sleep a normal eight-hour night, then subjected them to a night in which they were awoken four times by phone calls and asked to complete a 10- to 15-minute computer task before going back to bed.
Each morning-after, the volunteers completed more computer tasks and filled out questionnaires to determine their mood, alertness, and attention levels. After just one night of frequent interruptions, the experiment showed a direct link between disrupted sleep and compromised attention and mood.
The results are especially concerning to new parents, who are typically up three to ten times a night for months on end, says lead author Avi Sadeh. "We know that these effects accumulate, and therefore the functional price is enormous," he says.
It doesn’t have to be this way. Sadeh advises anyone with interrupted sleep to treat the underlying cause, ASAP—because it’s a lot harder to make up for lost sleep than to do it right the first time. Once you’ve asked the neighbors to keep it down, practice good sleep hygiene to keep the good shuteye consistent. Most importantly: Keep work (and the gadgets that remind you how much you need to do) out of the bedroom.
Bottom line: Interrupted nights don't give your body the restorative sleep it needs—and even brief wakenings will still disrupt natural sleep rhythm, says Sadeh. "Our study is the first to demonstrate seriously deleterious cognitive and emotional effects."