Idea behind the project

Usually, sleep and sex seem contradictory. You can’t do the one while doing the other. Our society, however, is more interested in sex and less in sleep. This has lead to a symposium of the American Association for Research in Personality in 2015 in St. Louis “The Neglected Third of our Lives: The Role of Sleep in Personality Processes”. Recent research found that there are differences between sleep duration (just in hours; how much hours you sleep) and sleep timing (When to sleep). Assume, you go to bet at 10PM and get up at 6AM, you sleep the same amount of hours like a person who goes to bed at 2 AM and sleeps until 10AM. The first person is a morning lark, the second a night owl. A lot of research showed that morning types “rule the world”. Have better achievement in school and University, higher business success, a more conscientious personality. Evening people on the opposite are more creative, more intelligent, more open and extraverted.

Now linking sleep timing and sex, our research group found that evening owls have higher mating success, as measured by questions about the lifetime number of sexual partners and extra-pair matings. But why is  this so? Is it just an accident? Or is it related to biology. There are some evolutionary hypothesis that can be checked, but in humans, it is more difficult than in other animals. Humans use contraceptives, plan their family sizes and so on. Therefore, our big interest is in the biological relations. We already found that testosterone is higher in evening men, one indicator. Now it is up to check additional questions. For example, immune system could be better in evening types, or sperm quality and quantity might be higher. We address these two questions in our research.