Evening exercise after a sedentary day increases sleep duration by nearly 30 minutes

A new study published in the journal BMJ Open Sport & Exercise Medicine assessed whether taking 3-minute strength training breaks in the evening improved the quantity and quality of sleep compared to sitting for long periods.

Insufficient sleep negatively impacts diet and increases the risk of cardiometabolic diseases such as coronary heart disease and type 2 diabetes. Evening exercise does not generally interfere with sleep and may improve sleep quality, but current recommendations advise avoiding physical activity before bedtime. The effect of regular evening activity breaks on sleep remains unclear, and further research is needed to assess the long-term impact of these breaks on sleep quality and overall cardiometabolic health.

This randomized, crossover study, conducted in Dunedin, New Zealand, examined the effects of evening activity breaks on sleep and physical activity patterns in 30 participants aged 18 to 40 years. Participants did not smoke, did not take medications that affect metabolism, and reported high levels of sedentary behavior. They wore the ActiGraph GT3X+ accelerometer for seven days to track their activity and sleep habits, while keeping a diary to record the time they were not wearing the device and sleep details.

Participants completed two 4-hour evening sessions: one with prolonged sitting and one with 3-minute strength training breaks every 30 minutes. Sessions were conducted on Tuesdays or Thursdays with a minimum of six days between sessions. Standard meals were provided before 2:00 p.m. on each experimental day, and participants followed pre-intervention protocols to avoid intense physical activity. Data were analyzed using mixed-effects regression models to compare sleep and

The study, conducted from March to October 2021, reached its target sample of 30 participants, primarily women of New Zealand European descent. Pre-intervention habitual accelerometry data showed that participants slept an average of 7 hours and 47 minutes, sat for 10 hours and 31 minutes, and were physically active for 4 hours and 55 minutes per day. Of the participants, 75% had optimal sleep duration, 21% had short sleep (<7 hours), and 4% had long sleep (>9 hours).

During the first night period, the regular activity break intervention significantly increased sleep period duration by 29.3 minutes compared with prolonged sitting (95% CI: 1.3 to 57.2, p=0.040).

Total sleep duration was also significantly longer by 27.7 minutes after activity breaks (7 hours and 12 minutes) compared with prolonged sitting (6 hours and 45 minutes) (95% CI: 2.3 to 52.4, p=0.033).

However, there were no significant differences between the two conditions in sleep efficiency, wake time after sleep onset (WASO), or number of awakenings. Participants' sleep attempt times were not significantly different, but awakening times were later after activity breaks (8:06 a.m.) compared to prolonged sitting (7:35 a.m.).

This study is the first to examine the effects of evening resistance exercise breaks on sleep quality and physical activity patterns in healthy adults. Results showed that regular activity breaks in the evening significantly improved leisure and total sleep time without affecting other aspects of sleep quality or subsequent physical activity.

This supports growing evidence that evening exercise does not impair sleep quality. Unlike high-intensity cardio, strength training can be easily integrated into evening routines without major disruption.

The study highlights the potential for evening exercise breaks to increase sleep duration and possibly improve long-term health outcomes.