As a general rule, regular running promotes better sleep. But there appears to be an exception: hard exercise in the hours before bedtime.<\/p>\n
That\u2019s the conclusion of a new study in the journal Nature Communications<\/a>. Looking at the sleep data of 14,000 WHOOP users, researchers investigated how timing and intensity of evening exercise affect sleep<\/a> and recovery.<\/p>\n They found that both intense or long workouts within four hours of bedtime had a detrimental impact on sleep onset (when you go to sleep) quantity (how long you sleep) and quantity (how well you sleep).<\/p>\n Exercise 6+ hours before bedtimeSleep onset<\/p>\n Six or more hours before \u2018habitual sleep onset\u2019 (i.e. the time you naturally nod-off), you can essentially exercise however you wish. In fact, high- and maximal-strain exercise \u2013 think high-intensity intervals<\/a> or a two-hour long run<\/a> \u2013 promoted marginally earlier sleep (by about 2-6 minutes).<\/p>\n Sleep quantity<\/p>\n All exercise intensities during this time window improved sleep duration. The higher the strain the better \u2013 you\u2019ll get an extra seven minutes off the back of a maximal-strain session.<\/p>\n Sleep quality<\/p>\n Surprisingly, sleep quality suffers during this window, regardless of the intensity or duration of the exercise<\/p>\n Exercise 4-6 hours before bedtime Sleep onset<\/p>\n Only light exercise \u2013 think a slow jog \u2013 had a sleep-promoting effect. Everything else (moderate, high and maximal workouts) was essentially neutral. In other words, they didn\u2019t affect sleep negatively or positively.<\/p>\n Sleep quantity<\/p>\n Slightly negative impact on sleep quantity, with harder exercise having the biggest impact.<\/p>\n Sleep quality<\/p>\n Suffers, regardless of exercise intensity or duration<\/p>\n Exercise 2-4 hours before bedtimeSleep onset<\/p>\n During this window, any type of exercise was associated with a later sleep onset. Specifically, moderate-to-maximal exercise four hours before bedtime delayed sleep onset by 8-20 minutes.<\/p>\n Sleep quantity<\/p>\n Exercise conducted within four hours of bedtime had a negative effect on sleep duration \u2013 contributing to around a nine-minute reduction.<\/p>\n Sleep quality<\/p>\n Surprisingly, light exercise in this window actually marginally improved sleep quality. All other categories of exercise \u2013 from moderate to maximal \u2013 had the opposite effect.<\/p>\n Exercise 0-2 hours before bedtimeSleep onset<\/p>\n This is where things get more serious. Moderate-to-maximal intensity exercise within two hours of bedtime delays sleep by a fairly significant 11-36 minutes.<\/p>\n Sleep duration<\/p>\n Expect a 30-minute reduction in sleep quantity. As with sleep onset, the effects are dose-dependent: the closer you exercise to bedtime and the higher the exercise strain, the less you\u2019ll sleep that night.<\/p>\n Sleep quality<\/p>\n Not impacted by light exercise (i.e. a slow jog), but negatively impacted by intensities higher than this.<\/p>\n What can you do about it?<\/p>\n If you do find yourself running hard in the evening \u2013 say, during a Tuesday night track session \u2013find a way to bring your core temperature down: it\u2019s probably the biggest factor affecting your sleep post-exercise. A cold shower or bath<\/a> are two practical options.<\/p>\n