Those who hit the hay before 10:30pm have better sperm quality.
A groundbreaking study's found that men who go to bed early increase their chances of fathering kids.
Scientists in the Netherlands tracked 104 men with an average age of 34 over a two-year period, studying their sleep patterns and sperm samples.
They discovered that those who went to bed at 10:30pm had nearly four times greater sperm quality compared with those who went to sleep at 11.30pm or later.
They also found that men who got between seven and a half and eight hours sleep produced sperm which appeared six times healthier than that of those who got less than seven hours.
The researchers at Aarhus University believe a lack of shuteye pressures the immune system into attacking healthy sperm.
It also puts men under physical and psychological stress.
