Interrupting Sitting with Evening Exercise Boosts Sleep by Nearly 30 Minutes

In a recent study published in the BMJ Open Sport & Exercise Medicine, researchers assessed if evening 3-minute resistance exercise breaks enhance sleep quantity and quality compared to prolonged sitting.

Study: Evening regular activity breaks extend subsequent free-living sleep time in healthy adults: a randomised crossover trial. Image Credit: faithie/Shutterstock.com

Background 

Insufficient sleep negatively impacts diet and increases the risk of cardiometabolic diseases such as coronary heart disease (Blocked heart blood supply) and type 2 diabetes (High blood sugar due to insulin issues).

While evening exercise generally does not disrupt sleep and can improve sleep quality, current guidelines advise against it before bed.

The effect of regular evening activity breaks on sleep remains unclear. Further research is needed to explore the long-term impact of evening activity breaks on sleep quality and overall cardiometabolic health.

About the study 

This randomized crossover trial in Dunedin, New Zealand, examined the effects of evening activity breaks on sleep and physical activity patterns in 30 participants aged 18-40.

Participants were non-smokers, free from medications affecting metabolism, and reported high sedentary time. They wore an ActiGraph GT3X+ accelerometer for seven days to track habitual activity and sleep, maintaining a diary for non-wear and sleep details.

Participants completed two 4-hour evening sessions, either prolonged sitting or sitting with 3-minute resistance exercise breaks every 30 minutes, conducted on Tuesdays or Thursdays with a minimum six-day washout period.

Standardized meals were provided before 14:00 hours 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 activity outcomes between conditions. 

Study results 

This study, conducted from March to October 2021, reached its intended sample size of 30 participants, predominantly women of New Zealand European ethnicity.

Pre-intervention habitual accelerometry data showed participants averaged 7 hours and 47 minutes of sleep, 10 hours and 31 minutes of sedentary time, and 4 hours and 55 minutes of physical activity daily. Among participants, 75% had optimal sleep duration, 21% were short sleepers (<7 hours), and 4% were long sleepers (>9 hours).

During the first nocturnal period, the intervention of regular activity breaks significantly increased sleep period time by 29.3 minutes compared to prolonged sitting (95% CI: 1.3 to 57.2, p=0.040).

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

However, the two conditions had no significant differences in sleep efficiency, wake after sleep onset (WASO), or the number of awakenings. The times participants attempted to sleep did not significantly differ, but wake times were later following the activity breaks (8:06 am) than prolonged sitting (7:35 am).

No significant differences were observed in physical activity patterns in the 24 hours following each intervention.

The regular activity breaks resulted in 18 minutes less total physical activity and 1.6% less waking time being active compared to prolonged sitting, although these differences were not statistically significant (95% CI: −50.3 to 13.8, p=0.265; 95% CI: −4.6 to 1.4, p=0.289).

Health-promoting effects of regular activity breaks included total sleep time (effect size 0.38 SD, 95% CI: 0.01 to 0.75) and increased sleep period time (effect size 0.42 SD, 95% CI: 0.01 to 0.82) with a small, non-significant decrease in sedentary time.

Changes in sleep efficiency, total physical activity, WASO, and the number of awakenings were all small and non-significant (effect size <0.3).

Over the entire 48-hour period following each intervention, no significant differences were observed in measures of sleep or activity. The mean difference in sleep period time for regular activity breaks compared to prolonged sitting was 0 minutes (−20.5 to 20.5, p>0.999). 

Conclusions 

This study is the first to investigate the impact of evening resistance exercise breaks on sleep quality and physical activity patterns in healthy adults.

The results showed that regular activity breaks in the evening significantly improved free living and total sleep time without disrupting other aspects of sleep quality or subsequent physical activity.

This supports the growing evidence that evening exercise does not impair sleep quality. Unlike high-intensity cardiovascular exercises, resistance exercise breaks can be easily integrated into evening routines without major disruptions.

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