The University of Bristol-led study analysed sleep data from activity monitors worn by 11,800 people over the Spring and Autumn clock changes in 2013-2015. The study is unique in that it analysed objectively-measured sleep in a large number of people in the UK who are signed up to UK Biobank. 

It is commonly thought that people lose an hour of sleep in Spring (when the clocks go forward an hour) and gain hour of sleep in Autumn (when the clocks go back an hour). Previous research also suggests that people get less sleep for around a week after both clock changes as they find it difficult to adapt to the new time.

Whilst this new study did find that people slept around an hour less on the Sunday of the Spring clock change than the previous and subsequent Sundays, they did not (or could not) take advantage of the full extra hour of sleep in Autumn. In fact, they only slept for just over half an hour more than the surrounding Sundays.

The study also found that the effect on sleep for the rest of the week differed depending on gender. Men tended to sleep more on the weekdays after both clock changes, although this was more pronounced in Spring. However, this pattern of catch-up sleep was not seen for women. They often slept for less on the weekdays after the clock changes than before. This could be because women experience higher levels of insomnia and sleep difficulties, and that these problems are exacerbated by the clock changes.

Read the full University of Bristol news item

‘The effects of daylight saving time clock changes on accelerometer-measured sleep duration in the UK Biobank’ by Melanie A de Lange, Rebecca C Richmond, Kate Birnie, Chin Yang Shapland, Kate Tilling & Neil M Davies in Journal of Sleep Research [open access]