An evening meal and drinks out can help you sleep better and feel more refreshed, but going for brunch has the opposite effect and makes you more tired, study finds.
Researchers from the Karolinska Institute, Sweden, studied the behaviour and sleepiness of 641 working adults in Sweden, particularly on weekends and days off.
Sleepiness can impair cognitive ability, motivation, and behavior including on our desire to socialise with others, according to the team led by Benjamin Holding.
The relationship between social activity and subsequent sleepiness and sleep duration was complex and depended on the time of day, the team found.
Going out for brunch can make you more sleepy in the afternoon and sleep less at night, going out for dinner can make you more refreshed and sleep better.
According to the authors, uncovering factors that may interfere with social activity could help address rising rates of loneliness and social isolation.
As part of the study volunteers logged their behavior every 30 minutes, filled out a sleepiness scale every three hours, and completed a sleep diary every morning.
Together, the findings suggest that sleepiness is tied to a drop in people wanting to go out and socialise – particularly in the evening or when you have a day off.
Increased social activity during the late morning and early afternoon was tied to greater sleepiness afterward – so going for brunch can make you more tired.
However, actually going out in the evening, even if you are sleepy, can reduce the sleepiness, make you feel more refreshed and help you sleep better at night.
‘The influence of sleepiness appears most prominent at times when socialising is most likely to occur, such as in the evenings and during days off,’ the team wrote.
‘It may be that sleepiness is most likely to influence social contact when individuals have the freedom to choose their activity, thus allowing changes in social motivation to become more influential on behavioural choices.’
The study, carried out over a three week period, found that daytime sleepiness was an ‘important driver of human motivation and behaviour’.
‘We observe that a change from very alert to very sleepy can decrease social contact by approximately 70 per cent,’ the team wrote in their study.
They say that it provides a perspective on possible mechanisms behind sleep disturbances – from shift work or medicine – are linked with poorer health outcomes.
‘It is especially urgent to understand the causes of decreased social activity, as rates of social isolation and loneliness are reported to be rising, as are rates of sleep disturbance,’ the team wrote.
‘The results provide directions for future research, for example regarding whether interventions to alleviate sleepiness can be an effective way to improve both short- and long-term well-being.’
There were limitations to the research, according to the team behind the study, who said volunteers were only reporting their activities every 30 minutes.
This was designed to make the process manageable for participants but may have missed out on some social contact happening in shorter bursts.
‘For example, some activity categories, such as ‘freetime activity’ or ‘work,’ may include social interaction not accounted for in our analyses,’ the authors wrote.
‘Our definition of social activity was also broad, and there may be specific environments or types of social contact where the effect of sleepiness is greater.
‘There may also be particular sample populations that are more susceptible to the influence of sleepiness than others, and future research may benefit from investigating a greater variety of demographic groups.’
The research also involved older data – not recently collected information – that was gathered before the rise of social media as a factor in socialising.
The findings have been published in the journal Proceedings of the National Academy of Sciences.