When asked why they don’t exercise regularly, many people offer the excuse that there simply isn’t enough time in the day. It’s true that most of us are very busy, with long hours spent at work and/or handling family responsibilities, housekeeping chores, and errands. So oftentimes, any physical activity performed is squeezed in either first thing in the morning or later at night. This is hardly ideal for most people, however, as new research shows that it may cost us important slumber time.
The study, which was conducted at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia, found that an increase in exercise is associated with less sleep in those who exercise very early or late in the day.[fn] Yao, Christopher J. and Basner, Mathias. “Healthy behaviors competing for time: associations of sleep and exercise in working Americans.” Sleep Health. 25 October 2018. Accessed 28 November 2018. http://www.sleephealthjournal.org/article/S2352-7218(18)30180-3/abstract.[/fn] These results are based on an analysis of information gathered for the American Time Use Survey, which is a long-term collection of data by the Census Bureau. The subjects were 47,862 employed men and women between the ages of 18 and 65. They were interviewed on a weekday at some point between 2003 and 2016, and they reported everything they had done over the course of the prior 24 hours.
Not surprisingly on a weekday, the participants spent the bulk of their time either at work or commuting to and from work. Only 17 percent reported working out within the past 24 hours, which is even lower than the 22.9 percent of Americans who typically exercise regularly according to the Centers for Disease Control and Prevention’s most recent report. What’s more, the current study showed that longer hours spent at work was linked to both less exercise and fewer hours of sleep.
The volunteers who had worked out in the prior 24-hour period received 15.5 minutes less sleep on average than their counterparts who had not worked out. And as the length of exercise time increased, the length of time spent sleeping decreased. The most pronounced connection between these two competing needs occurred in those who performed their exercise between 6 a.m. and 8 a.m. or between 9 p.m. and 11 p.m.
When you think about the routines many of us keep, these outcomes make perfect sense. After all, chances are good that if you’re getting up to squeeze in some physical activity at a gym prior to work, you still have to shower, get dressed a second time, do a bit of grooming, and have some breakfast before you head off to work. Even a 30-minute workout means you will have to wake up a good 45 minutes or more earlier than you would if you weren’t exercising. And unfortunately, most of us will not go to bed 45 minutes earlier the night before, so it is sleep that is sacrificed.
At the end of the day, the situation is equally problematic since it likely results in a later bedtime, and with work the following morning, sleeping late to make up that lost slumber time is out of the question. On the bright side, however, the study showed that, other than those working out first thing in the morning before work or right before bed, people who exercised for one hour or less did not generally have a loss of sleep time. Therefore, if you choose to work out in the evening, keep your session prior to 9 p.m. and shorter in duration.
There are a few relatively easy fixes for you if managing exercise time and sleep has been a challenge. First of all, follow your natural rhythms as much as possible. So, if you’re an early bird with time to spare before work in the morning, do your workouts then without sacrificing sleep. Likewise, if you’re a night owl who would be staying up until past midnight anyway, put your evening time to better use with a workout session. And if early morning or nighttime physical activity means you’d be sacrificing sleep, find other options. Taking a brisk walk during your lunch hour, going straight to the gym from work, or dedicating a little time to exercise shortly before dinner can all be convenient even with a busy career.