I’ve been trying to figure out lately how much sleep I need. I used to assume I needed the standard 8 hours per night, but after tracking my time for multiple weeks over the years, I’ve realized that’s not the case. It tends to average out around 7.5 hours/day over a week (so 52.5 hours or so). I probably wake up every other night to go to the bathroom in the middle of the night, and sometimes it takes me a bit longer than other nights to get back to sleep, which lowers my actual total a bit from 7.5 hours.
But I don’t think I’m sleep deprived. I’m not pounding coffee all day. I have one cup in the a.m. On weekends I usually wake up pretty early (sometimes before the kids, sadly enough). Last night, the last time I saw on my clock was 10:45 and I woke up a few minutes before 6, which was long before I’d set my alarm. I’m sure this has something to do with summer and the early light, but I let myself lie there in bed and slowly open my eyes before hopping up around 6:15 to go for a run. Then again, other days I sleep a bit longer. I went to sleep around 11:20 on Monday night and woke up at 7:15 on Tuesday morning. We all got a slow start that day. Fortunately, the kids still made it to camp on time.
So I’ve been interested to see the reaction to a story in the Wall Street Journal yesterday suggesting that 7 hours, not 8, might be the right amount to get. As with all studies and recommendations, this is a tricky thing to say for sure. Generally, people say that “7-9 hours” is ideal for adults, but some analyses of broad studies and mortality data suggest that the lower end of that range is associated with lower risks. Again, you can’t control for everything. People who are ill might sleep more, but it’s not the sleeping more that’s the problem — it’s the underlying health condition. But it does suggest that getting less than 8 hours a night, and perhaps even a wee bit under 7, isn’t something to worry about.
Unless you’re falling asleep at the wheel. Then it is — and you need more sleep.
As I’ve been looking at data from the Mosaic Project, I’ve been realizing a few things. First, the vast majority of women in the project (about 90 percent) got at least 7-9 hours/day averaged over the week. Bad days were pretty rare. Only 37 of 1001 days featured less than 6 hours of sleep. No one averaged less than 6 hours/day when tallied over the whole week (42 hours over 7 days) but in my sleep section, I did look at the women who averaged between 6-7 hours/day, with the assumption that this was lower than ideal. Now that I know at least one study looking at 1.1 million people found that sleeping 6.5-7.4 hours was associated with lower mortality, I may have to reconsider the phrasing. Most people who were under 49 hours/week were over 45.5 hours (6.5 hours/day).
Of course, averages mean nothing about individuals, and if you need 8 hours/day and are getting 6.5, that can be a problem. But I shouldn’t assume, on its face, that getting a bit less than 7 hours is bad.
One other finding: When people think about sleep, they think about “typical” nights. But there are no typical nights. Just comparing two adjacent weekdays — Tuesdays and Wednesdays — I found that 22 percent of women showed gaps in sleep totals of 90 minutes or more. Sleep variances are frequent, and probably contribute to muddled findings on how much sleep people need.
How much sleep do you think you need? Do you get that most nights? Are there big variances?
In other news: Modern Mrs. Darcy has a guest post from a woman who managed to achieve big things in her personal life by shifting a mere 2 hours of her work schedule around. We often think that change requires a lot of shifting, but if you’re focused and mindful, you can do a lot with a little.
Photo: A hotel bed. I sleep extra well in these.