According to Yle, sleep disorders in Finland peak during the summer months when warmer temperatures and light may change sleep patterns.
The relatively short summer in Finland is an exceptional time of year for sleepers. The increased light and warmer temperatures tend to lead to people spending more time out of doors and more time socializing. Summer usually offers more events and activities of interest.
“The amount of light keeps one alert for longer periods at a time and sleep declines. In the winter sleep is often light and intermittent, but even so one gets more of it,” Partonen adds.