While male fertility is relatively straightforward, female fertility is governed by complex systems. The hormone levels of a fertile woman change by the day and even by the hour. Although we know a great deal about how monthly cycles affect female fertility, new research suggests that daily cycles, also known as the circadian rhythm, may also play a role.

The Cycles of Female Fertility

Women’s fertility is controlled by a complex system of internal clocks. Most fertile women have a monthly cycle that is roughly 28 days long. The first day is the day when menstruation begins. Two weeks later, most women ovulate and are fertile for just a few days. Levels of the hormones estrogen, progesterone, LH and FSH fluctuate widely to keep this internal clock on track.

Although these monthly cycles are important, there is evidence that our daily circadian rhythms also play a role. Understanding this connection may be an important part of solving the very common problem of female infertility.

Links Between Circadian Rhythms and Fertility

How does a dysregulated circadian rhythm affect fertility? While this is still a new area of study, it is clear that our sleep-wake cycles are as important as our monthly cycles in maintaining the ability to reproduce. Shift workers, or people who work unusual hours, are more likely to have menstrual issues and more than ten percent more likely to suffer from infertility.

In addition, there is a matter of proximity. The suprachiasmatic nucleus (SCN) of the brain controls our internal clocks. It also is responsible for controlling the release of LH, the hormone that signals the ovaries to release an egg. In addition, our ovaries appear to be partially controlled by Clock genes, which are the gene group most important in regulating circadian rhythm. As a result, LH is at its highest levels early in the morning.

Is this correlation a coincidence or proof of our circadian rhythms affecting fertility? Several new studies suggest the latter. In one experiment, scientists mutated the Clock genes of mice in a laboratory. Without any other changes in their environment, the mice began to have disrupted hormone levels, ultimately leading to lower fertility. Even plants appear to have some relationship between their circadian rhythms and fertility.

This link between sleep-wake cycles and fertility makes sense on an intuitive level. We are more likely to become pregnant if the hours of highest fertility occur at a time when we are awake. Evolution likely has affected the female body by helping women to ovulate when they are also more likely to find a partner. However, this effect has only been noted in women. While the ovaries express Clock genes, the testes do not.

The Bottom Line on Sleep and Reproduction

Getting enough sleep is crucial to maintaining good health. This is especially true if you are trying to conceive.

Women who have sleep apnea and other sleep disorders are three times as likely to experience infertility as women who have healthy sleep habits. In addition, women who are undergoing IVF and other fertility treatments have a higher chance of getting pregnant if they are getting seven to eight hours of high-quality sleep. If you are trying to get pregnant, getting plenty of sleep and keeping your circadian rhythms on an even schedule may increase your chances.

Although male fertility does not appear to be as affected by sleepless nights, it is still important for men to keep their sleep-wake cycles on a balanced rhythm. Not getting enough sleep is associated with lower sperm counts and also a lower sex drive in men, making sleep very important for their sexuality and ultimately their fertility.

Sleep: Crucial for Whole-Body Health

Whether you are trying to conceive or not, maintaining good sexual health is an important part of living a happy and fulfilled life. However, many modern people have lifestyles that make this difficult. If you are struggling to get the sleep you need, consider making the following changes to your daily routine:

• Keep a set daily schedule, sleeping, waking and eating at roughly the same times of the day.
• Expose yourself to plenty of bright light throughout the day while dimming lights (and smartphones!) at night.
• Use blackout curtains to reduce light pollution if you live in a heavily populated area.
• Keep a bedtime routine that helps you to feel relaxed when you climb into bed.
• Consider trying a melatonin supplement if you struggle to fall asleep even after making the above changes.

Getting enough sleep is important for your fertility, but more so for your overall health. If you want to live the healthiest and happiest life possible, keeping a steady circadian rhythm is an important lifestyle change.