Light and Fertility - How Sunlight Improves Reproductive Health

Light and Fertility: Science-Backed Strategies for Supporting Hormonal Health

If you’ve been to my laser clinic or I’ve written a fertility protocol for you for a home device you’ll know I ask a lot of questions about what kind of light you’re exposed to regularly.Before you invest in any more supplements, red light devices or acupuncture there’s a FREE tool that most women (and partners) aren’t optimizing, and it can have a big impact on reproductive health. (Invest in a nice eye mask first).

New scientific research, along with promising older pilot studies, shows that optimizing your light environment can play a transformative role in menstrual health and fertility. Fascinating studies from Mary Lee Barron and small clinical studies by pioneers like Joy DeFelice demonstrate that simple changes, like improving darkness during sleep can make a substantial difference for women trying to conceive.

Why Light Matters for Fertility

Light acts as the primary timekeeper for your body’s circadian rhythm, directly influencing reproductive hormones. Morning exposure to blue and red/orange wavelengths supports the release of FSH, LH, and estradiol, helping to ensure regular cycles and optimal ovulation. Melatonin, produced mostly in darkness, also guides progesterone production and luteal phase stability, and too much ambient light at night can disrupt these delicate hormonal signals.

Studies reviewed by Barron highlight how regular schedules, morning light, and limited exposure to artificial light after sunset lead to healthier cycles, increased ovulation, and greater chance of conception - particularly in women with irregular menstrual cycles or hormonal sensitivity.

Light Elimination Therapy (LET)

In one of her pivotal studies, Joy DeFelice followed 48 women over 10 years who were struggling with menstrual cycle irregularities. Each participant learned to chart her cycle using standard natural family planning techniques and provided a “light score” reflecting the amount of light present in her bedroom at night. Before adopting light elimination therapy, nearly all women had abnormal follicular phases, and over half had abnormal luteal phases, with the average light score starting at 37.5.

Participants were then asked to reduce nighttime light in their bedrooms as much as possible, continuing to track their cycles. Within six cycles, 26 women conceived - a conception rate in line with the general population. Notably, the average light score at the time of conception was just 4.6, an 87% reduction from baseline. Fifteen women achieved pregnancy in fewer than three cycles of improved darkness. Most striking is that most participants had previously consulted fertility specialists without success, yet over half conceived after implementing light elimination therapy. When the data were adjusted to exclude women who did not consistently follow the darkness protocol, the conception rate increased to 78%.

DeFelice also shared a meaningful case study of a couple who, after fifteen years of unsuccessful attempts, conceived in their fifth cycle after adopting light elimination therapy.

Some compelling results:

·       Before LET, none of the women had three consecutive cycles with all parameters normal; abnormalities were most often found in the follicular phase (96%), luteal phase (64%), and ovulation phase (58%).

·       After implementing LET, abnormalities fell sharply and became rare; over 54% (26 women) became pregnant within six cycles, a rate comparable to the general fertile population.

·       Two women with a history of repeated miscarriages carried pregnancies to full term.

·       Among women over 30, healthy conceptions were frequent, suggesting LET may help restore fertility even in older age groups.

·       Women who maintained darkness throughout pregnancy had healthy deliveries; previous miscarriage rates dropped significantly with strict LET.

·       Men also benefited, among couples where partners had abnormal fertility tests, half conceived after LET was implemented.

·       The pilot studies found that when light sources were reintroduced, abnormal cycle parameters tended to return, suggesting a strong connection between artificial light at night and ongoing cycle disruption.

Light elimination therapy (LET) may also hold promise for miscarriage prevention. In a follow-up study, Joy DeFelice worked with nine women who had each experienced a previous miscarriage and asked them to follow LET strictly during their next pregnancy. All nine women subsequently had healthy pregnancies and births. However, she reported two additional women with a history of miscarriage who did not adopt LET and experienced another miscarriage. Although a prior loss does not guarantee recurrence, national statistics would suggest that at least one miscarriage might have been expected among the group of nine. These outcomes point to the potential of LET as a supportive measure for women with a history of pregnancy loss, though further research is needed to clarify these effects.

These encouraging results indicate that sufficient darkness during sleep may provide a non-invasive, cost-effective way to support regular menstrual cycles, healthy hormone function, and even reduce the risk of miscarriage.

Practical Tips for Supporting Fertility

·       Morning sun exposure: Aim for 10–15 minutes of outdoor light after waking to align your body’s clock.

·       Limit artificial evening light: Reduce blue-rich light from screens and overhead bulbs after sunset. Opt for dim, warm lighting whenever possible (full spectrum lightbulbs are available online).

·       Create a dark sleep environment: Use blackout shades, consider sleep masks, and eliminate any stray light from outside or nearby rooms.

·       Chart cycles and stay consistent: Tracking cycle parameters can help monitor progress and further personalize your approach.

Some Good News Finally!

With evidence from Mary Lee Barron’s research and supportive pilot studies, it’s clear that optimizing your light environment has concrete benefits, better sleep, more regular cycles, improved ovulation, and higher conception rates, even for those who have faced long or difficult journeys. These are achievable, science-backed strategies that can empower women to support their reproductive health in accessible ways.

Yes, getting up at sunrise can be challenging for some but consider it a wise time investment in your reproductive health.

Tracy

Resources:

https://pmc.ncbi.nlm.nih.gov/articles/PMC11897534/pdf/RMB2-24-e12641.pdf

https://pubmed.ncbi.nlm.nih.gov/17601857/

https://www.fertilityfriday.com/joydefelice/