Summary: A new study suggests that three-minute resistance exercise breaks every 30 minutes in the evening can extend sleep time by an average of 27 minutes. This practice does not disrupt sleep quality and may reduce the risk of cardiometabolic diseases.
Participants performed simple exercises such as chair squats and calf raises. Further research is needed to confirm these results in real-world situations.
Highlights:
- Prolongation of sleep: Exercise breaks increased sleep by 27 minutes.
- No disturbance: Exercise did not affect sleep efficiency or cause nighttime awakenings.
- Impact on health: May help reduce the risk of cardiometabolic disease by prolonging sleep.
Source: BMJ
Resistance exercise and nighttime activity breaks may improve sleep duration, suggest the results of a small comparative study published in the open-access journal BMJ Open Sports and Exercise Medicine.
Three-minute breaks every 30 minutes over a 4-hour period may be sufficient, the findings suggest.
Current recommendations advise against intense exercise before bed because it increases body temperature and heart rate, which can lead to poor sleep quality, the researchers say.
While exercise breaks after a meal may improve metabolism, it is unclear whether they impact sleep. Poor sleep is associated with an increased risk of cardiometabolic disorders, such as coronary heart disease and type 2 diabetes, the researchers explain.
To explore this question further, the researchers recruited 30 nonsmokers aged 18 to 40. All reported spending more than 5 hours of sedentary time at work during the day and 2 hours in the evening.
To record physical activity and sleep patterns, participants wore an activity tracker continuously on their non-dominant wrist for 7 consecutive days. They were asked to record periods when they were not wearing it, the time they went to bed, and the time they woke up.
They were also asked to record any physical activity when they were not wearing the activity tracker, such as swimming or a contact sport, and to record activities that are known to be inaccurately identified by the tracker, such as stationary cycling or yoga.
Each participant completed two 4-hour sessions in a controlled laboratory environment on the same day of the week, starting around 5:00–5:30 p.m., and separated by a minimum period of 6 days.
In one session, participants sat for 4 hours; in the other, they performed 3 minutes of simple resistance exercises every 30 minutes over a 4-hour period. Participants then returned to their normal, real-world environment.
Each activity break consisted of 3 sets of 3 exercises: chair squats, calf raises, and standing knee raises with straight-legged hip extensions for 20 seconds each, to the beat of a video recording of a person performing the same exercises.
Activity tracking data showed that before the experiment, participants spent an average of 7 hours 47 minutes sleeping, 10 hours 31 minutes sitting, and 4 hours 55 minutes doing vigorous physical activity per day.
Three out of four people slept the recommended 7 hours per night, while the rest slept either less than that (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, compared to prolonged sitting.
The average sleep duration was 7 hours 12 minutes, compared with 6 hours 45 minutes after prolonged sitting. And while the time at which participants attempted to fall asleep was roughly the same, the average wake times differed. Participants woke up at an average of 7:35 a.m. after the prolonged sitting intervention and at 8:06 a.m. after regular activity breaks.
Additionally, no significant differences were observed in sleep efficiency (uninterrupted sleep) or the number of awakenings during the night between the two interventions, indicating that activity breaks do not disrupt subsequent sleep, the researchers say.
No statistically significant differences were observed in activity patterns over the 24 hours following each intervention. But compared with prolonged sitting, regular activity breaks resulted in 18 minutes less physical activity overall, or less than 2% of total waking time.
The researchers acknowledge that their findings have some limitations. For example, the study involved a small number of participants and was conducted in a laboratory setting, which may not reflect real-world behavior.
Further studies involving a larger number of people in their usual home environment, and over a longer period, are therefore necessary, the researchers stress.
But they nevertheless say: “These results add to a growing body of evidence indicating that evening exercise does not disrupt sleep quality, despite current sleep recommendations that indicate otherwise.”
And they point out: “Adults accumulate the longest periods of sedentary behavior and consume almost half of their daily energy intake in the evening, and insulin sensitivity is lower at this time.”
By extending sleep duration, particularly in those who sleep less than the recommended nightly total, activity breaks may potentially reduce the risk of cardiometabolic disease in the long term, they suggest.
The resistance exercises used in their study are simple to perform, require no equipment, and can even be done while streaming content, potentially increasing the chances of sticking with the routine, they add.
But they point out: “Although existing research indicates that evening exercise may not negatively impact sleep, the mechanisms by which it influences sleep quality remain unclear.”
About this exercise and sleep research news
Author: BMJ Group Media Relations
Source: BMJ
Contact: BMJ Group Media Relations – BMJ
Picture: Image credited to Neuroscience News
Original research: Free access.
“Regular evening activity breaks prolong subsequent free sleep time in healthy adults: a randomized crossover trial” 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 trial
Objective
To determine whether regular 3-minute resistance exercise sessions over 4 hours in the evening will impact subsequent sleep quantity and quality, sedentary time, and physical activity compared with prolonged, uninterrupted sitting.
Methods
In this randomized crossover trial, participants each completed two 4-hour interventions beginning around 5:00 p.m.: (1) prolonged sitting and (2) sitting interrupted by 3-minute breaks of body-weight resistance exercise every 30 minutes.
After the study was completed, participants returned to a free-living environment. This article presents secondary outcomes of sleep quality and quantity, physical activity, and sedentary time that were assessed using wrist-worn ActiGraph GT3+ accelerometers combined with a sleep and wear time diary.
Results
A total of 28 participants (female, n=20), aged 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 duration and time spent asleep by 29.3 min (95% CI: 1.3–57.2, p = 0.040) and 27.7 min (95% CI: 2.3–52.4, p = 0.033), respectively, on the evening of the intervention.
No significant effects were observed on mean sleep efficiency (mean: 0.2%, 95% CI: −2.0 to 2.4, p = 0.857), wake time 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
Evening physical activity breaks may improve sleep duration and total sleep time without disrupting other aspects of sleep quality or subsequent 24-hour physical activity. Future research should explore the long-term impact of evening activity breaks on sleep.
Trial registration number
Australian and New Zealand Clinical Trials Registry Platform (ACTRN12621000250831).