In the past it was usual for women to say to their husbands or lovers, ‘Not tonight darling… I am too tired.’ But a role reversal is now more the domain of men. It seems that when it comes to a night of passion or a night of nod, it’s men who are more likely to enjoy snoozing than engaging in sex. And to whom do we owe this myth-breaking scientific finding? Come forward 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 Nitabash, Professor of Genetics at Yale University, who co-wrote the study, suggested that 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. Humans could possibly have a similar mechanism for adjudicating when the drive for sleep and sex collide.’

But the findings contradict human behaviour studies that have found almost two thirds of married women would rather go to sleep, watch a film or read a book than have sex with their partners. The fruit fly study published in the journal, Nature Communications, involved depriving the flies of sleep for 12 hours, to see if they would be more amorous afterwards. And if you are wondering how to keep a fruit fly from nodding off, the scientists apparently shook them every now and then to keep them awake. The research team, which included the South East 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 6 hours a night have waists 3cms thicker on average than those who manage 9 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 reduce blood levels of the good form of cholesterol, HDL, which 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 7 to 9 hours is the best for most adults.’ The findings are published in the journal, Public Library of One.

I have always regarded the importance of sleep as vital to keep a healthy body in great working form and boost sexual desirability in both male and females. So my advice – get cracking, sleep more and enjoy life to the full in competition with hovering fruit flies around you who, apparently know more about sex than humans do!

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