Culled from Warren Ellis' blog:
Sharing a bed with someone could temporarily reduce your brain power - at least if you are a man - Austrian scientists suggest.
When men spend the night with a bed mate their sleep is disturbed, whether they make love or not, and this impairs their mental ability the next day. The lack of sleep also increases a man’s stress hormone levels. According to the New Scientist study, women who share a bed fare better because they sleep more deeply...
That makes sense, as far as evolution goes — if males are sexually sated but on edge and more violent, they’re more likely to reproduce (and defend that genetic inheritance so that it survives to reproduce.)
there was a suggestion that women are pre-programmed to cope better with broken sleep. "A lot of life events that women have disturb sleep - bringing up children, the menopause and even the menstrual cycle," he explained.
I'm not a morning person at the best of times... but it goes some way towards explaining why, no matter what size the bed, I dislike sharing one. For sleep, anyway. I'm pre-programmed to awaken at the first sign of disturbance and club sabre-toothed tigers to death...
Incidentally, whoever picks images and does captions for the BBC site must have fun.