Not tonight, dear... tired men prefer sleep to sex (at least that’s what a fruit f ly’s love life reveals)

NOT tonight, darling, I’m too tired. If you think that sounds like a woman talking, you’d better think again.

It seems that when it comes to a night of passion or a night of nod, it’s men who are more likely to prefer snoozing to sex.

And to who do we owe this myth-breaking scientific finding? Er, fruit flies.

Experts who believe that the fly’s brain operates similarly to ours discovered that females will still respond to male advances even when they are tired.

Sleep-deprived males, on the other hand, showed little interest in courtship.

Michael Nitabach, professor of genetics at Yale University who co-wrote the study, suggested this is because males looking to pass on their genes cannot afford to fall asleep in the act. But females cannot afford to pass up an eligible suitor, no matter how tired they are.

He said: ‘It appears that whichever behaviour has the highest biological drive suppresses the other behaviour.’ Professor Nitabach said humans could possibly have a similar mechanism for adjudicating when the drives for sleep and sex collide.

But the findings contradict human behaviour studies that have found almost twothirds of married women would rather go to sleep, watch a film or read a book than have sex with their partner. The fruit fly study, published in the journal Nature Communications, involved depriving them of sleep for 12 hours to see if they would be amorous afterwards. And if you’re wondering how to keep a fruit fly from nodding off, the scientists apparently simply shook them every now and then to keep them awake.

The research team, which included Southeast University in China and the University of San Diego, also found sexually aroused males got little sleep, while aroused females slept more.

Previous research in humans has shown that women’s sex drive gets stronger the longer they sleep, with each extra hour of a lie-in putting them more in the mood.

In another study, it was found that poor sleep could make you fatter. People who sleep for six hours a night have waists 3cm – 1.18inches – thicker on average than those who manage nine hours.

Scientists compared sleep patterns and waist circumference in 1,615 adults.

They found shorter sleepers not only had wider waists, but were heavier.

Sleeping for shorter periods was also linked to reduced blood levels of the ‘good’ form of cholesterol, HDL, that helps to keep arteries healthy.

Lead researcher Dr Laura Hardie, from the University of Leeds, said: ‘Our findings highlight the importance of getting enough sleep. The current consensus is that seven to nine hours is best for most adults.’

The findings are published in the journal Public Library of Science ONE.