Men who want to become fathers should also get their shut-eye. That's because a man's fertility begins in the brain, not as a thought, but as a pulse of hormones. Every 70 to 90 minutes of every day, and every night, a gland in the brain called the hypothalamus sends a pulse of a hormone called gonadotrophin releasing hormone (GnRH) to another gland in the brain called the pituitary. The pituitary in turn sends follicle stimulating hormone (FSH) to the testes to stimulate the growth of long, shaft-like follicles that will eventually release sperm. The hypothalamus sends out more GnRH during sleep. Men who get at least six to seven hours of uninterrupted sleep produce more sperm. And getting uninterrupted sleep depends on another hormone, called melatonin. The pineal gland, which is also in the brain, makes melatonin only when the eyes do not sense blue light. Even when the eyelids are closed, even if the light source is just a crack in the door or an opening in the curtains, the retina can sense enough blue light to send a message to the brain not to make melatonin.
Through most of human history, this mechanism made it easier to stay awake during the long days of the summer. But in modern times, if you want to sleep, you have to turn the lights out - or at least make sure any nightlight you have on emits light just in the yellow spectrum. This tiny change enhances fertility. Men seeking to become fathers may also benefit from changes in sexual technique. When it comes to conception, variety in sexual positions is not a good thing. The ejaculate is sent further into the cervix when the man is on top, in the missionary position. The sperm has a shorter path to the egg and is more likely to remain viable long enough to fertilize it. It always takes two to conceive, of course. These changes, however, may be exactly what a couple needs to reach success in trying to conceive a healthy child.