Written by Valicia Burke-France. Reviewed by Jenny Wordsworth. Valicia is a women’s health writer with over 10 years of experience.

Light exposure and circadian rhythms play a vital role in reproductive health and fertility. In this article, we cover the connection between circadian rhythms and fertility by exploring the link between light, sleep, and reproductive health. We also share practical steps for optimising fertility naturally and to help improve reproductive outcomes.

Understanding Circadian Rhythms

Have you ever wondered how your body knows when it is time to wake up or when you need to rest? As humans, our bodies have evolved to align with the rhythm of a solar-driven cycle. Many of us “wake” with the sun and “rest” at night. In fact, all of our bodies' natural processes and changes occur in a cyclical rhythm over a 24-hour period in a system regulated by our biological clocks. This rhythm is referred to as circadian rhythm, and almost every tissue and organ in our body has its own circadian rhythm. As a result, circadian rhythms influence every aspect of how our bodies function, including sleep, hormonal cycles, temperature, and more.

Role of Biological Clocks

The biological clocks that regulate our innate sense of our many circadian rhythms are each made up of proteins created by genes that turn on and off in a particular order. These clocks are all regulated by a master clock in our brains consisting of nerve cells that form the suprachiasmatic nucleus (SCN).

One of the SCN’s functions is to produce the hormone melatonin according to the amount of light in our environments. So, for example, when it's dark at night, the SCN produces more melatonin, which tells our bodies it’s time to go to sleep. Conversely, melatonin levels are highest during the daytime, when exposed to more light.

Melatonin, the Wake-Rest Cycle, and Your Overall Health

Sleep and alertness are two key parts of one of our most critical circadian cycles — the wake-rest (also known as sleep-wake) cycle. Sleep patterns significantly impact essential daily functions, such as memory, healing, hormone release, and other bodily functions. Irregular and detrimental sleep habits are linked to various health challenges, ranging from mood or mental health disorders (such as depression and bipolar disorder) to endocrine disorders (such as diabetes). The wake-rest cycle is primarily driven by the changes in melatonin levels.

Additionally, the hypothalamic-pituitary-gonadal axis, which is the system responsible for the development of the reproductive system, is controlled through hormones. Research has revealed a clear bi-directional relationship between melatonin levels and sex hormones. Poor sleep can negatively alter hormone regulation, affecting levels of reproductive hormones oestrogen and progesterone and other widely influential hormones, like the stress hormone cortisol.

Research investigating the link between low melatonin levels and pregnancy and birth complications indicates that melatonin can help promote more successful pregnancy outcomes and birth and maternal recovery experiences. Melatonin, which is a prescription drug in the UK, has antioxidant properties that may improve egg quality for optimised fertility and may prove helpful regarding advanced aged fertility and improved IVF outcomes. The sleep hormone may also help prevent certain diseases in the family from being passed down to children.

Altogether, these findings emphasise the critical relationship between hormonal balance and sleep.

Impact of Light Exposure on Circadian Rhythms

Light has a more powerful impact on human circadian rhythms than any pharmaceutical product, and as our circadian rhythms are driven by the sun cycle, disruption in our light exposure patterns is detrimental to our health. Unfortunately, many modern-day technologies use artificial lighting that can interfere with our light-driven cyclical processes.

For example, the blue light component of sunlight which is highest during the day, is emitted by technologies with LED screens, such as our computers and cell phones. Exposure to LED light has been shown to suppress and delay the increase in melatonin, which speaks to the connection between blue light and fertility. Even low-level lighting typically found in our homes can be detected by our body while our eyes are closed, affecting our wake-rest cycle and (subsequently) multiple other circadian rhythms.

Circadian Disruption and Reproductive Health

Studies exploring the connection between circadian rhythms and fertility have shown that individuals experiencing circadian disruption due to shift work, jet lag, and daylight savings times may experience decreased success regarding their fertility goals and pregnancy outcomes. In addition, specific clock genes have been linked to the surge in luteinising hormone (critical to ovulation), decreased fertility, and increased rates of miscarriages. Such data demonstrates the importance of exploring the connection between light exposure and ovulation when it comes to understanding the impact of light on reproductive health.

Circadian Synchronisation for Optimal Fertility

While more research is needed to understand the connection between circadian rhythms and egg health fully, one thing is clear – maintaining the balance of our natural, cyclical biological processes is important to our reproductive health. If you’re ready to support your body in creating optimal conditions for conception, keep reading for applicable tips you can implement today.

Balancing Light Exposure, Sleep, and Hormones for Reproductive Health

Optimising fertility naturally can be achieved by supporting your circadian rhythms by balancing your light exposure, sleep, and hormone cycles.

Tip #1: Regulate your light exposure.

Due to the connection between light exposure and ovulation, regulating your exposure to light is important. To avoid unwanted changes in the circadian phase or night-time sleep, light exposure in the evening, at night, and in the morning needs to be controlled.

Embrace sunlight upon waking. Spend a few moments in the sunlight upon waking. If seasonal changes make this challenging, especially with modern-day schedules and needs, consider using sun lamps to help.

Limit blue light exposure before bedtime. Ideally, we should reduce the time spent on devices using blue light within two hours of bedtime. You can use blue light features that are more commonly applied in the settings of modern devices and apps. Purchasing blue-light glasses or detachable screens may be your best option for older devices.

Due to the connection between blue light and fertility and the expansive use of blue light technology in our environment, regulating our exposure to these artificial light sources is essential.

Consider other sources of artificial lighting. The worrying impact of light on reproductive health extends beyond blue light sources. Exposure to artificial lighting at night comes in many easily overlooked forms, such as clocks, chargers, and even power strips in the bedroom. You can try to find alternative products without light or with features to turn off the light setting, safely cover or block lights at night, or simply move devices outside the bedroom.

Tip #2. Improve sleep hygiene.

Improving sleep hygiene will support your overall health and help regulate hormones such as melatonin and cortisol, critical to reproductive health. You can help improve your hormonal balance and sleep hygiene in various ways.

Establish a regular sleep schedule. Establishing a regular time to wake up and rest can support you in falling asleep better and faster each night. Determine how many hours of sleep you need, and set a specific time for bedtime and waking up each day. Ideally, adults need between 7 to 9 hours of sleep each night. The ideal amount of sleep for you is the one that leaves you feeling rested when you wake up and alert throughout the day.

Set a calming bedtime routine. You can fall asleep easier at night by adopting a calming routine. Ideas vary from person to person, ranging from warm baths, reading, meditative practices, or listening to calming music. Generally, it’s important to avoid stimulants or super energetic activities within a few hours of bedtime.

Start darkening your bedroom to prepare for sleep. Further reduce the negative impact of light on reproductive health goals by controlling light exposure before you go to sleep, avoiding using blue light–emitting devices within an hour of bedtime, and removing or hiding artificial light sources throughout the room. Use blackout curtains, which is helpful in seasons when the daylight may stretch beyond your bedtime, and for blocking artificial lighting from lamp poles, car lights, security lights, and more.

Tip #3: Adapt other important healthy lifestyle habits.

Practising healthier habits helps improve the efficiency of all our biological processes, including supporting our reproductive health.

Follow a healthy diet. A healthy diet is one that provides you with all the minerals and nutrients your body needs and is achieved by having a well-balanced diet. In addition, using recommended supplements can provide your body with the resources needed to work effectively.

Exercise consistently each week. Exercising has many benefits, including improving mood, stress levels, sleep quality, energy levels, sexual health, and sex life. If you’re just starting out, start slowly with a gentle but effective exercise, such as walking. It is recommended for adults to exercise at least 75 minutes of vigorous activity or 150 minutes of moderate activity per week. Just be sure to avoid vigorous activity too close to bedtime, as it can impact your healthy sleep goals.

Manage your stress. Cortisol levels increase during times of stress, and high levels of cortisol have been linked to issues with infertility. Stress-management techniques, such as yoga, deep breathing, and meditation, can help lower stress.

Key Takeaways on Light and Circadian Rhythms

Poor sleep, stress, or irregular light exposure can disrupt circadian rhythms, which may, based on initial studies, lead to issues such as infertility and poor pregnancy and birth outcomes. Since circadian rhythms and fertility are closely connected, syncing your routines with natural rhythms can support hormonal balance and may support your fertility. In addition to fertility, aligning your light exposure with your circadian rhythms can improve your overall quality of life and promote long-term health.