Laziness and your love life

It might be a stereotype that men are lazier than women, that we’re real-life Homer Simpsons who like nothing more than a lie in, and, as with many stereotypes, it’s partly true and partly false.

Men tend to stay in bed longer than women, but they also prefer to go to bed later, if only because staying up until dawn is the only way they can get in a five hour session on Modern Warfare 3. All in all, men actually get less sleep than women.

But why is it that men are more likely to be evening people, and women to be morning people? Some researchers have suggested that a male propensity to burn the midnight oil might be a product of evolution, with natural selection favouring men who can stay up later. For example, the traditional division of labour between men and women—with men responsible for hunting and women for gathering—may have promoted shorter sleep duration in men (although this does rather ignore the fact that women in hunter-gatherer societies spend much of their time rearing children, so it’s surprising they get any sleep at all).

There’s also evidence that in some hunter-gatherer communities, men are obliged to dance through the night as a way of wooing women. Men who can go without sleep are able to dance longer, and presumably find it easier to secure a partner. Again, it’s difficult to see how this could cause a sex difference in sleep patterns, because if women are unable to stay awake to judge men’s dancing skills, the men are presumably wasting time that would better spent catching up on their beauty sleep.

Nevertheless, investigations in modern societies have suggested a preference for staying up late—which psychologists rather clumsily term “eveningness”—is associated with greater success in the mating game. Men with a propensity for eveningness—men who stay up later—tend to have more sexual partners.

But is this relationship down to the fact that most social activities take place at night, thereby giving men who can fend off the sandman an advantage? Or is there some other link between eveningness and luck with the ladies?

Christoph Randler and colleagues from the University of Education in Heidelberg, tackled this question in a study out this month. They first assessed the preferences of 284 men for late nights over early mornings, then collected data on these men’s social life, including what times they preferred to go out, and for how long. Amongst these German students in their early 20s, the average sleep duration was 7 hours and 18 minutes, a figure that manages to both bolster the stereotype of hard-working Germans and destroy the cliché of the perpetually dozing student.

The researchers found that men high in eveningness stayed out longer and had more sexual partners. They also had more sexual partners who already had a partner of their own, suggesting that staying up late provides greater opportunity for cuckolding other men. Because morning and evening people didn’t differ in overall sleep duration, the advantage of being an evening person might be than it allows you disproportionate access to the pool of prospective partners.

Put another way, if you’re asleep, you can’t have it away with another man’s girlfriend. Or play Xbox with a 14 year old boy from Wichita. Both very good excuses for not getting up until noon.

Randler, C., Ebenhöh, N., Fischer, A., Höchel, S., Schroff, S., Stoll, J. C., et al. (2012). Eveningness is related to men’s mating success.Personality and Individual Differences, 53, 263–267. Read summary

The content of this post first appeared in the May 2012 episode of The Psychology of Attractiveness Podcast.

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