A new study by Monash University has highlighted a significant correlation between bedtime hours and previous physical activity the next day, because it revealed that going to bed earlier can improve daily exercise levels.
This study, published in the Proceedings of the National Academy of Sciences (PNA)was led by researchers from Monash Uniferisty who analyzed a large set of data collected from laptops worn by nearly 20,000 people over one year, which gives about six million data points on sleep and activity.
Although the study does not establish a relationship of cause and final effect, its results offer valuable information to public health initiatives aimed at improving physical activity thanks to better sleep habits, according to Scientific alert.
“These ideas have significant implications for public health,” said psychologist Josh Leota of Monash University. “Rather than simply promoting sleep and physical activity independently, health campaigns could encourage times to sleep earlier to naturally promote more active lifestyles.”
The results indicated a clear trend: an anterior bed hour is constantly aligned with a more moderate to vigorous exercise the next day.
For example, participants who went to bed at 9 p.m. recorded an average of 30 minutes more than those who retired at 1 a.m. and 15 minutes more than those with a bedtime at 11 p.m. (which was the average of all participants).
The duration of sleep also played a role, but with a nuanced result.
Those who have an average of five hours of sleep recorded 41.5 minutes of additional exercise compared to those who have an average of nine hours. However, researchers warn that the advantages of an increase in exercise in this scenario could be thwarted by the negative effects of sleep deprivation.
The most intriguing conclusion was perhaps that individuals who went to bed earlier than their usual time, while retaining their typical sleep period, tended to reach personal records in time of activity the following day.
The researchers offer several explanations of these observations.
Subsequent bedtime could be revealing of generally busy people, and time to sleep earlier could reduce the probability of sleeping too much or hitting the repetition button on several occasions – although specific awakening times are not part of the study data.
“Standard routines from 9 to 5 can compete with the natural sleep preferences of the evening types, leading to a social jetlag, a lower quality of sleep and increased dayless sleepness – which can all reduce motivation and physical activity opportunities the next day,” said Leota.
The study meticulously controlled factors such as age, body mass index and that the day was a weekday or a weekend.
In addition, a similar relationship, although less pronounced, was observed in a second more diverse data set of 5,898 individuals, strengthening the initial results.
Although this study establishes a strong correlation, it is important to note that it does not definitively prove causality. Other underlying factors, such as the natural predisposition of an individual as “night owl”, could contribute both to later levels of sleep and to lower exercise levels. Additional research is necessary to fully unravel these variables.
“Sleep and physical activity are both essential to health, but so far, we do not fully understand how intimately they are connected in everyday life,” said psychologist Elise Facer-Childs, also from Monash University.
“Our results are consistent in different populations and show that if you can fall asleep earlier than usual while keeping your sleep time, you might be more likely to increase your physical activity the next day.”
