The current study included 59 participants (72% female) with a minimum age of 35 years, who worked at least 35 hours per week, and who started at a baseline of walking less than 60 minutes per day.
The participants were randomly assigned into one of two groups:
- The intervention group, who monitored their steps for one week to get a baseline activity level, and then increased their steps by 2,000 a day;
- The control group, who were not given a step goal.
Both groups were provided with support on how to use their Fitbit to monitor their activity. The participants completed self-reported questionnaires during the study period of four weeks.
The collected data was used to determine whether a correlation existed on both a daily and a monthly basis between increased activity levels and improvements in sleep quality and duration.
When examined over a month, increased activity levels were related to improvements in overall sleep quality, but not sleep duration. It was found that women experienced greater benefits from bouts of acute activity. On a daily basis, increased exercise improved that same day’s sleep quality.
It is speculated that improved sleep quality is probably more important (and easier) to obtain through physical activity than increased sleep duration, as other factors such as schedule conflicts and outside responsibilities (such as with work and family) may make it harder for people to increase their sleep duration with increased physical activity alone.
> From: Sullivan Bisson et al., Sleep Health 5 (2019) 487-494 . All rights reserved to National Sleep Foundation. Click here for the online summary.
Expert opinion
This article highlights the important role between physical activity and sleep, and utilised a common activity tracker to investigate this, which makes the ecological validity of this study very high, i.e. achievable for a large population. Moreover, the researchers also set a realistic walking goal, and found a positive correlation between sleep and activity, particularly in women.
However, this study did have some limitations: there was a disproportionate number of female participants, and the self-reported questionnaires for sleep quality and sleep duration were not described in detail. A standardised outcome measure, as well as using other technology (such as a sleep monitor, for instance) could have led to other or at least more detailed outcomes than just self-reporting.
All this aside, this article does make a compelling case for the importance of exercise for sleeping well, especially with the growing number of people worldwide who struggle with this each night.
