In the field of time use, it’s one of the great questions. Everyone thinks Americans are increasingly sleep deprived. Giant surveys such as those done by the National Sleep Foundation often provide evidence of this. And yet the American Time Use Survey consistently shows that Americans — even those who work and have young kids — sleep 8-plus hours per day.
Why the difference? A key issue is that the NSF’s annual survey has historically asked about a typical night (see the 2008 summary of findings, p. 10 shows charts for a “typical” night). We may build our lives in ways that don’t seem to allow for enough sleep in a normal day’s schedule. Yet we may sleep at unscheduled times. That sleep gets counted in a time diary, and is at least one of the reasons that the totals are different.
I was thinking of this during this past weekend, when I completely conked out on Saturday afternoon. I’d probably been averaging about 7 hours of sleep a night over the previous few days. Not bad, really. But when my 2-year-old fell asleep at 2 p.m. on Saturday, I lay on my bed to read a novel, and promptly fell asleep myself. I woke up at 4:40 p.m. when my husband put the (awake and whining for mommy) toddler on top of me.
I’m not suggesting that most people have that experience. But this extra sleep can affect an average a great deal. If I slept 7 hours a night for 7 days, but then added in an extra 160 minutes of napping at some point, that gets me to a daily average (calculated weekly) of about 7:23.
That’s not drastically different, I suppose, but there turn out to be lots of occasions for unscheduled sleep. People set their alarms, and then hit snooze three times. Getting an additional 27 minutes of sleep on one morning, averaged over 7 days, adds 4 minutes per day to the total. And people who hit snooze 3 times don’t generally just do this one day per week. Falling asleep at 9 p.m. in front of the TV one night, instead of the “typical” 11 p.m. adds 17 minutes to the daily average. Do it twice and you’ve added more than half an hour. Sleeping in on weekends, of course, can up a daily average (though the National Sleep Foundation does distinguish between weekday nights and weekend nights, and the ATUS too — and in both cases the ATUS totals are higher).
There’s also the matter of what we consider “typical.” Not all weekdays may be exactly the same, but if we’re feeling particularly tired, we may remember the one that involved staying up until midnight working as typical, instead of the good ones. All this contributes to different totals in our minds, vs. what would actually be recorded in a diary.
Of course, the question of whether bad nights are mitigated by unscheduled sleep isn’t a completely settled one. Runners who get a bad night of sleep right before a race tend to do OK if they’ve had good nights prior. On the other hand, most sleep doctors say you can’t completely make up a deficit on weekends. From seeing hundreds of time logs, my take-away is that each person tends to require a certain amount of sleep, and one way or another most of us who aren’t tending to 2-week-old babies get it. If you need 7 hours, and your “typical” night only accounts for 6, you’ll fall asleep in front of the TV on Wednesday night and oversleep your alarm on Friday. That late arrival at work wasn’t part of the schedule, but the sleep still happened.
Do you have unscheduled sleep in your life?