Resume: A new study suggests that three minutes of resistance exercise every 30 minutes in the evening can increase sleep duration by an average of 27 minutes. The practice does not disrupt sleep quality and may reduce the risk of cardiometabolic disease.
Participants performed simple exercises such as chair squats and calf raises. More research is needed to confirm these findings in real-life settings.
Key Facts:
- Sleep extension: Exercise breaks extended sleep by 27 minutes.
- No disturbance: The exercise did not affect sleep efficiency and did not cause nighttime awakenings.
- Health effect: May help reduce the risk of cardiometabolic diseases by extending sleep.
Source: BMJ
Strength training ‘activity breaks’ at night may improve sleep duration, according to the findings of a small comparative study published in the open-access journal BMJ Open Sports and Exercise Medicine.
The findings suggest that a three-minute break every 30 minutes over a four-hour period may be sufficient.
According to the researchers, current recommendations suggest against intense exercise before bedtime, as it increases body temperature and heart rate, which can lead to poorer sleep quality.
While breaks from activity may improve metabolism after a meal, it is unclear whether they affect sleep. Poor sleep is associated with an increased risk of cardiometabolic diseases, such as coronary heart disease and type 2 diabetes, the researchers explain.
To investigate this further, the researchers recruited 30 nonsmokers, aged 18 to 40, for their study. They all reported spending more than 5 hours sedentary during the day at work and 2 hours in the evening.
To capture habitual physical activity and sleep patterns, participants wore an activity tracker continuously on their non-dominant wrist for 7 days. They were asked to record the time they were not wearing it, the time they went to bed, and when they woke up.
They were also asked to record physical activities when they were not wearing the activity tracker, such as swimming or contact sports, and activities that were known not to be accurately identified by the tracker, such as stationary bikes or yoga.
Each participant completed two four-hour sessions in a controlled laboratory environment on the same day of the week, beginning around 5:00-5:30 PM, at least six days apart.
In one session, participants remained seated for 4 hours; in the other, they performed 3 minutes of simple resistance exercises every 30 minutes for the 4-hour period. Participants then returned to their normal, real-world environment.
Each break consisted of 3 rounds of 3 exercises: chair squats, calf raises, and standing knee raises with extended hip extensions for 20 seconds each, timed to a video recording of someone doing the same exercises.
The activity tracker data showed that before the experiment, participants slept for an average of 7 hours and 47 minutes, sat for 10 hours and 31 minutes, and engaged in vigorous physical activity for 4 hours and 55 minutes.
Three out of four slept the recommended 7 hours per night, while the rest slept less (21%) or more than 9 hours (4%).
The results, based on 28 participants, show that after activity breaks, participants slept an average of 27 minutes longer than when they sat for longer periods.
The average sleep duration was 7 hours and 12 minutes, compared to 6 hours and 45 minutes after prolonged sitting. And while the time at which participants attempted to go to sleep was more or less the same, the average wake times differed. Participants woke up on average at 7:35 a.m. after the prolonged sitting intervention and at 8:06 a.m. after regular activity breaks.
Additionally, there were no significant differences in sleep efficiency (uninterrupted sleep) or the number of times participants woke up during the night between the two interventions, indicating that breaks in activity did not disrupt subsequent sleep, the researchers said.
There were no statistically significant differences in activity patterns in the 24 hours following each intervention. But compared with prolonged sitting, regular activity breaks resulted in 18 minutes less total physical activity—less than 2% of total waking time.
The researchers acknowledge several limitations to their findings. For example, the study included a small number of participants and was conducted in a laboratory setting, which may not reflect real-life behavior.
More research is therefore needed, involving larger numbers of people in their normal home environment for a longer period of time, the researchers emphasize.
But they say nonetheless: “These results add to a growing body of evidence suggesting that evening exercise does not disrupt sleep quality, despite current sleep recommendations to the contrary.”
And they point out: “Adults experience the longest periods of sedentary life and consume almost half of their daily energy intake in the evening, with insulin sensitivity being lower at this time.”
By extending sleep duration, especially in people who sleep less than the recommended total night’s sleep, exercise breaks may reduce the risk of cardiometabolic disease in the long term, they suggest.
The resistance exercises they use in their study are easy to perform, require no equipment, and can even be done while streaming content, making it more likely you’ll stick with the routine, they add.
But they stress: “Although existing research suggests that evening exercise may not negatively impact sleep, the mechanisms by which [it] influence on sleep quality remains unclear.”
About this news about exercise and sleep research
Author: BMJ Group Media Relations
Source: BMJ
Contact: BMJ Group Media Relations – BMJ
Image: The image is attributed to Neuroscience News
Original research: Open access.
“Regular evening activity breaks increase subsequent free sleep time in healthy adults: a randomized crossover study” by Jennifer T Gale et al. BMJ Open Sports and Exercise Medicine
Abstract
Regular evening activity breaks prolong subsequent free sleep time in healthy adults: a randomized crossover study
Objectively
To determine whether performing regular strength training exercises of 3 minutes spread over 4 hours in the evening affects the amount and quality of sleep, sedentary time, and physical activity compared with prolonged uninterrupted sitting.
Methods
In this randomized crossover study, participants each completed two four-hour interventions, beginning approximately 5:00 PM: (1) prolonged sitting and (2) sitting interrupted by three-minute breaks of bodyweight resistance exercises every thirty minutes.
Afterwards, participants returned to a free-living environment. This article reports secondary outcomes related to sleep quality and quantity, physical activity, and sedentary time that were assessed using wrist-worn ActiGraph GT3+ accelerometers in combination with a sleep and wear-time diary.
Results
Total 28 participants (females, n=20), age 25.6±5.6 years, body mass index 29.5±6.7 kg/m2 (mean±SD) provided data for this analysis. Compared with prolonged sitting, regular activity breaks increased mean sleep period time and time spent sleeping by 29.3 min (95% CI: 1.3 to 57.2, p=0.040) and 27.7 min (95% CI: 2.3 to 52.4, p=0.033), respectively, on the evening of the intervention.
There was no significant effect on mean sleep efficiency (mean: 0.2%, 95% CI: -2.0 to 2.4, p=0.857), awakenings after sleep onset (1.0 min, 95% CI: -9.6 to 11.7, p=0.849) and number of awakenings (0.8, 95% CI: -1.8 to 3.3, p=0.550). Subsequent 24- and 48-hour physical activity patterns were not significantly different.
Conclusions
Performing bodyweight exercises in the evening may improve sleep duration and total sleep time and does not disrupt other aspects of sleep quality or subsequent 24-hour physical activity. Future research should investigate the long-term impact of evening activity breaks on sleep.
Trial registration number
Australian New Zealand Clinical Trials Registry (ACTRN12621000250831).