Do you notice that some health habits or nutrition tools tend to work better for you at certain times, and at others, it feels like you’re swimming against the current? Feeling well shouldn’t be hard work, which is why understanding the importance of aligning with your circadian rhythms can be a key way to support your wellbeing.
Reconnecting To Your Natural Rhythms
Women are inherently rhythmic beings. Before the industrial revolution and the introduction of artificial lighting, 9-5 jobs and more time spent indoors, women’s bodies and minds were more deeply connected to nature and its rhythms. In fact, a study published by Science Advances shows that for thousands of years, women’s reproductive hormonal cycles were intimately in-tune with the moon’s light and gravitational pull. Around 2010 however (with the introduction of smart phones) everything started to change. From studying 3000+ menstrual cycles, researchers found that menstrual cycles used to significantly align with the moon, with menstrual onset often falling near full or new moons, especially before 2010. This research suggests that increased exposure to LED lighting, screens and bright night time lighting, is disrupting our underlying biological sensitivity to lunar cues, and our circadian rhythms.
Key takeaway: Research has found that artificial lighting may be a significant factor in disrupting circadian rhythms and the menstrual cycle.
What are circadian rhythms?
Put simply, circadian rhythms are your body’s 24-hour internal timing system. They act like a biological clock that tells your body when to wake up, feel alert, when to release hormones, when to digest food best, and when to repair and sleep. The main clock sits in the brain (in an area called the suprachiasmatic nucleus), and it is primarily set by light — especially morning sunlight. Every major system in your body runs on this timing system — including your hormones.
Your Circadian Health
Circadian health is a growing nuanced area of health, and it’s one that could have a significant impact on your wellbeing. Research shows that the varying levels and waves of sunlight throughout the day can have a significant impact on our mood, energy levels, and even our hormonal balance. In fact, a fascinating study conducted back in 1989 shows how significant nature’s rhythms and sunlight is for hormone health:
An Italian interior designer named Stefania Follini voluntarily lived alone in a cave for around 130 days, with no sunlight, clocks, calendar or outside communication as part of a study on human circadian rhythms. Without sunlight, her body’s sleep-wake cycle shifted to almost 25 hours, and her menstrual cycle lengthened significantly. At one point she experienced amenorrhea (temporary absence of menstruation), and her hormonal rhythms became irregular.
This – alongside many other studies – is an example of how menstrual cycles are tightly connected to circadian biology, and how the amount of natural light we’re exposed to really can impact us in a big way. The reproductive system depends on co-ordinated timing between the hypothalamus, pituitary gland, ovaries and melatonin, which is a light-sensitive hormone. Without enough sunlight, melatonin secretion can become disrupted, which has a knock-on effect on our natural surge of luteinising hormone, potentially causing delayed or suppressed ovulation and missing or lengthened menstrual cycles. From an evolutionary perspective, it kind of makes sense; reproduction is timed to favourable seasons, and if the brain interprets an unstable or dark environment for too long, it may down-shift fertility temporarily.
So, what does this all mean in simple terms? It shows us that the amount of natural sunlight you get each day really matters, and that by taking small steps to align yourself with nature’s rhythms, it may significantly contribute to overall wellbeing and hormone health. If you’re entering menopause and no longer menstruating, this is important for you too, as research shows getting plenty of morning sunlight in particular is important for supporting good quality sleep, which can become disturbed due to menopausal hormonal fluctuations, and that by regulating circadian rhythms of menopausal women, hot flashes may even reduce in intensity and frequency.
Key Takeaway: Your circadian rhythm is your body’s internal 24-hour clock, and it’s largely controlled by natural light — especially morning sunlight. When you don’t get enough natural light, this clock can drift, disrupting sleep, mood, and hormone balance, including menstrual and reproductive health. The key takeaway is that regular exposure to daylight helps keep your hormones, sleep, and overall wellbeing in sync — even during menopause.
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Why is reconnecting to your rhythms important?
Think of the way a plant grows in nature; it waits for the right temperature, the right amount of sunlight, the right amount of rainfall and the right level of nutrients in the soil before it’s able to sprout or bloom. It relies on having the right conditions in which to thrive.
In the very same way, our bodies need the right conditions both internally and externally – often via cues from light and darkness - when it comes to feeling our best. Of course, in the modern world we can override nature, but that doesn’t mean we should.
When we reconnect to nature’s rhythms, we align ourselves with an invisible, unspoken support that can help life feel more like a flow than a struggle. To support female hormonal health and overall wellbeing, there’s no single magic solution - combining lifestyle and nutrition is key. Here’s how we would work on realigning our circadian rhythms alongside a healthy lifestyle and nutrient-dense foods:
Sunrise
Rich in natural blue light, this type of sunlight naturally re-sets the sleep-wake cycle and suppresses melatonin to tell the body ‘nighttime is over’. As cortisol levels naturally rise sharply upon waking, the morning light helps to stabilise reproductive hormones and ovulation rhythm. Women who connect with morning light consistently are shown to have more regular and ovulatory cycles, improved PMS in some cases, as well as less brain fog and improved blood sugar balance, which is vital when it comes to issues like PCOS.
Putting it into practice:
· Open a door or window ASAP after waking and look outside. The minimum effective dose on a sunny day to have a substantial effect is generally 5-10 minutes on a sunny day, and 15-20 minutes on a cloudy day. If you wake up way before sunrise, a 10,000 lux light box can mimic morning sunlight and support wakefulness.
· You can save time by stacking this healthy habit on top of something you already do. Think about viewing morning sunlight when you sip your morning coffee, take a morning walk, meditate, exercise, or even roll your car window down if you’re driving to work in the morning to let the natural light stream into the car.
· Research shows that eating your breakfast outside in natural morning sunlight may help improve insulin sensitivity and blood sugar balance too, so when the weather permits, try having breakfast alfresco.
Midday
Sunlight is generally at its peak around midday, and this can help boost serotonin for a more balanced mood and calm focus. In Spring and Summer, vitamin D is more available at midday too, supporting estrogen synthesis, progesterone balance and thyroid function. Low levels of vitamin D are linked to PMS symptoms of cramps, anxiety and fatigue, PCOS and even infertility. Whilst it may not be a magic pill, getting plenty of midday sunlight can be supportive for hormonal health, and also supports a healthy metabolism.
Putting it into practice:
· Eat your lunch outside in natural daylight
· Take a break from work for a walk in nature
· If you’re indoors at midday, open a window or door and position yourself so you can see natural sunlight
Sunset
With warmer orange light waves, sunset signals a ‘wind down’ cue to the body, and sets the scene for a rise in melatonin for better quality sleep. Sunset light also encourages cortisol to lower and can support progesterone stability as well as reduced anxiety.
Putting it into practice:
· Take a moment to watch the sun set
· If your work day has been stressful, create a boundary between work and personal time by taking a walk in the early evening
· Eat your dinner outside
Evening
Alongside morning sunlight, the amount of light we’re exposed to at night has a significant impact on hormonal health. Natural darkness at night supports melatonin secretion to promote restorative sleep and hormonal balance. Women often have higher natural melatonin levels than men, making the ‘darkness signal’ particularly important for sleep-wake cycles. Plenty of research now also shows that exposure to bright light at night has a significant impact on female hormone health, and is even seen as an ‘endocrine disruptor’. Blue light from screens or bright overhead lights at night suppresses melatonin, elevates cortisol, disrupts blood sugar balance and may even contribute to irregular cycles, increased PMS and higher levels of anxiety. Women tend to be extra sensitive to the effects of bright light at night, and hormones like estrogen and progesterone interact very closely with sleep hormones like melatonin.
Putting it into practice:
· After sunset, turn indoor lighting down or off if it is safe to do so.
· Avoid bright lights and screens at night. Use low lamps, red lightbulbs or candlelight instead
· If you’ll be watching TV in the evening, consider wearing blue light blocking glasses to mitigate some of the effects
· Women’s bodies tend to have a slightly shorter natural circadian rhythm and earlier body clock than men, meaning their bodies are ready for sleep earlier, so try to get to bed before 10pm.
· Support yourself with the right supplements and nutritional practices, like eating dinner early, using magnesium bisglycinate, or trying our Dusk capsules to support relaxation and sleep.
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The Essentials:
· Women’s bodies have historically been closely aligned with natural rhythms, such as the moon and sunlight, but modern artificial lighting and screen exposure have disrupted these cycles, affecting menstrual and hormonal health.
· Circadian rhythms, driven largely by natural light—especially morning sunlight—regulate essential body functions including hormone release, sleep, mood, and metabolism.
· Regular exposure to natural light at key times of day (morning, midday, sunset) supports hormonal balance, mood stability, reproductive health, and overall wellbeing.
· Evening and nighttime exposure to bright or blue light disrupts melatonin production, negatively impacting sleep quality and hormonal cycles, with women being particularly sensitive to these effects.
· Practical habits like spending time outside in natural light, reducing screen and bright light exposure after sunset, and using supportive supplements can help realign circadian rhythms and improve female hormonal health.