Sleepiness affects cognitive performance, motivation and behaviour. More and more people are suffering from sleep disorders, but the effects of sleepiness on social activity, which plays an important role in one’s overall health and well-being, have remained relatively unknown. In order to increase our understanding in this area, researchers at Stockholm University and Karolinska Institutet studied 641 working adults residing in Sweden. Participants recorded what they were doing every thirty minutes, estimated their level of sleepiness every three hours and filled out a sleep diary every morning for three weeks.

The results, which have now been published in the scientific journal PNAS, show a clear association between sleepiness and social activity. Higher levels of sleepiness could be linked to a reduction in the number of social activities and the amount of time one engaged in social activity, with the most significant effects seen on days off and during the evenings.