How Sleep Impacts Fertility

We all know how important logging enough sleep is for our overall health and our mood. That’s because when we sleep, the body doesn’t just rest. There are critical processes that need to happen during sleep, including solidifying memories and information, changing the release of hormones, and flipping DNA switches to turn off some genes and activate others, including those involved in reproduction.

So, it’s not surprising that inadequate sleep can also affect fertility. This can be especially challenging for shift workers and those who work nights. Here, we explore how abnormal sleep patterns affect the body—and what to do about it.

What is the circadian rhythm and what does it mean for hormones?

The circadian rhythm, A.K.A. the sleep-wake cycle, is the pattern that the body uses to regulate being awake and being asleep with respect to daytime and nighttime. Daylight, specifically blue wavelengths of light, suppresses the sleep hormone melatonin to discourage sleep, while at night, the absence of light, in combination with lower cortisol (stress hormone) levels, allows the body’s melatonin to increase, prompting sleep.

Your reproductive hormones, such as thyroid stimulating hormone (TSH) and prolactin, also have circadian patterns as their concentrations change in relation to sleep-wake patterns. It’s the same reason why postpartum, breast milk is most abundant in the middle of the night, compared to during the day. Researchers also say that levels of the sex hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are affected by disrupted sleep patterns, most notably shift/night work.

And if you’re producing less melatonin, it can also negatively impact fertility. Apart from being a sleep hormone, melatonin is an antioxidant that helps protect eggs before they’re ovulated. On the male side of fertility, melatonin affects testicular function, sex hormone levels, and protects against sperm DNA damage, all of which plays a role in conceiving.

How does nighttime shift work impact fertility?

Working irregular hours and/or nights forces changes to bedtime, which often leads to less sleep. These changes to sleep times cause melatonin to be suppressed and disrupts the circadian rhythm. This can have many negative effects. It can impair blood-sugar and insulin regulation which is one cause of early pregnancy loss. It also increases oxidative damage to cells and DNA and changes hormone levels which can affect ovulation. In male fertility, animal studies have shown that irregular sleep can decrease testosterone levels and reduce sperm motility.

In a human observational study, pooling data from seven European countries, it was reported that couples who were trying to conceive took longer to get pregnant—on average 9 months or more—if the person with eggs worked shift work. In pregnancy, the fetus is also sensitive to irregular sleep hours. In one study, pregnant people who worked rotating or irregular hours had lower birth weight babies compared to those who worked standard day shifts.

Fortunately, there are several tools shift workers can use to help reduce these risks and optimize sleep.

How to sleep better

1. Keep a regular sleep routine and bedtime. That schedule might change depending on if you have rotating shifts, but you can set your bedtime accordingly for the day/night you have. Stick to your bedtime and try not to stay awake longer, aiming for at least seven and a half hours of sleep per night.
2. Manage and decrease life stress. Cortisol, our stress hormone, blunts natural melatonin levels. Consider listening to a guided meditation or journaling before bed. Gratitude journals like “The Five Minute Journal” by Intelligent Change can help with self-reflection—even if you’re low on time. (We love this journal so much that we included it in Bird&Be’s self-care Gift Boxes!) You can also take supplements that support stress management and encourage relaxation. Bird&Be's Calcium + Magnesium + Vitamin D Boost includes both Magnesium (great for encouraging relaxation before bed) and Vitamin D (which helps to reduce feeling of anxiety and depression). Bonus: They work better when taken together.
3. Take a Melatonin supplement. Taking Melatonin can help initiate and maintain sleep, and can be used by night and shift workers to improve levels in the body. Supplementing with as little as 3 mg a night has been shown to improve the outcome of IVF cycles such as increasing the number of eggs retrieved, and improving egg and embryo quality. Another study looked at males who underwent surgery for varicocele (enlarged, tangled blood vessels in the scrotum) and gave some a Melatonin supplement while others took a placebo for three months. The result? Those who took Melatonin had significant improvements in sperm concentration, motility, normal morphology and a greater total antioxidant capacity.
4. Avoid screen use an hour or two before bed. Remember, blue wavelengths of light can suppress melatonin, so the goal is to avoid exposing your eyes to it. If you have to use a device in the evening, try a blue light filter on your screen or wear eyeglasses that filter blue light.
5. Avoid caffeine for six to seven hours before bedtime. The caffeine in coffee, tea and colas can act as a stimulant for hours, depending on your genetics and how well you metabolize caffeine.
6. Keep your bedroom “cave-like.” You’ll want your sleeping quarters to be dark, quiet and slightly cool. Use blackout window shades, an eye mask, or ear plugs to help you get those perfect conditions.