It obviously makes sense that spending more time in bed with your partner would equate to more chances to get pregnant. More opportunities to have sex equals a greater likelihood of having a baby, right?

Well, scientists have said this isn’t the only reason more time in bed is good for your fertility prospects. New research suggests both men and women benefit from more sleep and a stable bedtime routine. 

The University of Miami study looked at data from 2996 men and found that men experience a 1.5 per cent drop in testosterone for every hour of sleep lost.

Testosterone is important for men’s fertility as it is the hormone which regulates your sex drive as well as playing a key role in the development of male reproductive tissues such as testes and prostate, and secondary sexual characteristics like muscle and bone mass, and the growth of body hair.

This is the first study to link sleep with a drop in the hormone and adds to the weight of research that says environmental factors, such as drinking, smoking and being overweight, can all damage your testosterone supplies.

And it seems sleep is one of the most important, as an hour of sleep lost is worse than drinking a beer, according to the scientists.

Channa Jayasena, a consultant in reproductive endocrinology at Imperial College London, said: “Anything that lowers a man’s testosterone is likely to be bad for them. We already know that obesity, diabetes and alcohol can do this.”

So should couples be worried about getting eight hours if they’re trying to have a baby? The authors of the study on men said yes, improving sleep could be considered as a treatment for men with low testosterone.

But Jayasena said the study doesn’t fully answer why poor sleep lowers testosterone levels. “One possibility is that sleep loss interferes with brain signals which are normally needed to stimulate testosterone release.”

And Ying Cheong professor of reproductive medicine at Southampton University, agrees that taking the results at face value was short-sighted as there are other factors at play. “Men should not jump to the conclusion about lost sleep decreasing their manliness or sexual prowess,” she said.

And burning the midnight oil isn’t just bad news for men: a separate study Washington University in St Louis found women who were trying to conceive and went to bed at a regular time were more likely to become pregnant than those with chaotic bedtime routines.