A new study has found that staying up late to watch movies or catch up on emails could affect men’s sperm count and damage their chances of fathering children.
Men trying to have a baby could increase their chances of getting their partner pregnant if they go to bed before 10.30 at night.
The study also found that men with an early bedtime are almost four times more likely to have good-quality sperm.
It's been discovered that sleep deprivation can cause the immune system to overreact and attack sperm, while going to bed too late may see couples run out of time to have sex.
Scientists asked men what time they've been going to bed over the past month. Those who went to bed before 10.30pm were almost four times more likely to have normal sperm than men whose bedtime was 11.30pm or later.
Professor Hans Jakob Ingerslev, co-author of the study from Aarhus University, said: "These were men who had been trying to have a baby for about two years and an early bedtime was likely to be important because it allowed them to get more sleep.
"The reasons could be psychological as sleep-deprived men suffer mores stress and that can have an impact on fertility."
Dr Raj Mathur, a consultant gynaecologist at Manchester University NHS Foundation Trust, who was not involved in the study, said: "The study suggests men who are trying for a baby should be going to bed early and getting a decent amount of sleep.
"They should think about what is keeping them up and try to change their habits, whether it's binge-watching Netflix or sending emails.
"Going to bed earlier with their partner may also increase their opportunity for sex, improving their chances of success further."
Researchers found men who went to bed before 10.30pm were 2.75 times more likely to have normal sperm than those with who went to bed later, say between 11pm and 11.29pm.
Men who slept for between seven-and-a-half and eight hours more often had normal sperm, boosting their ability to have a baby naturally.
The results suggest they were six times more likely to have good-quality sperm than those who slept less than seven hours a night on average.
Dr Christopher Barratt, professor of reproductive medicine at the University of Dundee, said: "Telling men who are trying to conceive to get more sleep is a very sensible message, although this is a small study.
"If you don't get enough sleep, that has an impact on the metabolism, which will have a negative effect on sperm quality.
"It is pretty basic advice but a lack of sleep is closely tied to feeling stressed and stressed men are also less likely to have sex once a day, as we recommend when trying for a baby."