On Sunday, June 21, it will be light in the center of the country for no less than sixteen hours and 45 minutes. In the north even a little longer, in the south a little shorter. Anyway it’s the longest day. What does that actually do to a person if it is already light at 5:19 a.m. and it doesn’t get dark until 10:04 p.m.? Chronobiologist Karin Smolders from Eindhoven University of Technology knows all about it.

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