When most men trying to start a family have an early start each day for work, experts say getting enough sleep is crucial.
Evidence suggests 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.
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 ‘early’ before 10.30pm were 2.75 times more likely to have normal sperm than those with a more ‘regular’ bedtime between 11pm and 11.29p