Couples often have differences of opinion with regards to their sleeping preferences. Some like it cold, some like it warm, some want lots of blankets, some prefer very few. One topic of discussion is the presence of light in the bedroom. There are those who swear by blackout curtains. Others prefer to have a nightlight on or even the windows open to allow fresh air (and outside light pollution) in. But the presence–or absence–of light during sleep is not merely a matter of personal preference. It’s a choice that could have implications for fertility and healthy childbirth. Enter light elimination therapy.
Light Elimination Therapy
The practice of removing all light while sleeping is called Light Elimination Therapy (LET). Setting up a darkened environment for better sleep is not a new idea. But LET has come up more recently in women’s health circles because of its connection with improved fertility and menstrual cycle regularity. Joy DeFelice, a registered nurse who directs the Natural Family Planning Program at a Spokane, WA hospital, examined the relationship between LET and female fertility in two small research studies and one case study.
In her first study, 48 women were taught how to chart their cycles according to standard natural family planning methods. They were followed over the course of 10 years. These women all had various irregularities in their menstrual cycle. Almost all of them had an abnormal follicular phase, and more than half had an abnormal luteal phase. DeFelice also had them rate the presence of light in their room, with a mean score of 37.5.
Participants were directed to reduce the light score while continuing to chart. Within six cycles, 26 women became pregnant (which is a “normal” rate of conception). 15 of those women became pregnant in even less time. What is more significant is that the “light score” at the time of conception for all of these women was 4.6, over 87% reduced from their original light score. Furthermore, most of these women had consulted with a physician previously regarding fertility, with no positive result. But after LET, over half of them conceived. DeFelice also noted that 15 of the women applied LET inconsistently, and perhaps should not have been included in the overall group. If these participants were excluded, the overall rate of conception jumped to 78%.
DeFelice also presented a case study of a couple who, after trying for 15 years, conceived in their fifth cycle after implementing LET.
The connection between light exposure and fertility
The absence of light triggers your brain to produce melatonin, which helps you to sleep. The less light you’re exposed to, the better. Melatonin production, when it’s normal, runs on a 24 hour cycle. Its levels are lowest during the day and highest at night. Sufficient exposure to darkness is helpful (as well as sufficient exposure to sunlight during the day). Melatonin, as DeFelice has written elsewhere, affects the hypothalamus gland in your brain “which is the cycling center for the woman’s reproductive hormones.” The thinking goes that disruptions in melatonin production can not only harm your sleep, but your reproductive cycle, as well.
LET and miscarriage
The potential implications of LET for miscarriage prevention are also fascinating. DeFelice, in her second study, took nine women who previously had miscarriages and instructed them to apply LET strictly in their next pregnancy. All nine went on to have healthy pregnancies. She also mentioned two other women who had had miscarriages, chose not to apply LET, and went on to have second miscarriages. While a previous miscarriage is not necessarily an indication of another miscarriage, nevertheless, according to national rates, at least one of those nine mothers would have been expected to miscarry.
How to implement LET
Light Elimination Therapy has a complicated name but a simple methodology. Eliminate as much light as possible in your bedroom. This includes artificial and natural lights, both inside and outside of the house. Blackout curtains do well to block light from outside, and most people do not have bright lights in their bedrooms. But even the smallest sources of light need to be covered or removed. This includes light coming in from under the door, digital clocks, phone chargers, etc.
As Marilyn M. Shannon put it in her book, Fertility, Cycles, & Nutrition, “Light rays are quite capable of penetrating the eyelids, and in dim light, the retina is exquisitely sensitive even to very low levels of illumination” (Shannon, 186). Any sort of light sends signals to the brain to reduce melatonin, so a good rule of thumb is to make the room dark enough that you can’t see your hand held in front of your face. Additionally, electronic devices such as cell phones, tablets, laptops, and televisions should be turned off at least thirty minutes before bedtime. Shannon points out that small disruptions during the night such as using the bathroom or breastfeeding should not be enough to throw off this melatonin rhythm, so long as the light stays dim and is not on for too long.
Can too much darkness be a problem, too?
More darkness isn’t always the answer, however. Too much melatonin can disrupt reproductive hormones as well–in a study done on Finnish women, who experience longer winter nights because of their proximity to the North Pole, melatonin levels were high, but levels of LH were found to be low . Sufficient levels of daylight seem to be necessary for a healthy level of melatonin at night. In fact, watching the sunrise and the sunset could help with this melatonin cycle, and even a mere fifteen minutes spent outside during the day is beneficial.
More research on LET is needed
DeFelice’s work has not been published in a peer-reviewed journal. But it has laid the groundwork for future research into the potential of LET for treatment of infertility. Future research should also explore whether there is a true connection between LET and lowered risk of miscarriage, since DeFelice’s observations point to a relationship. Larger sample sizes and rigorously conducted studies are necessary to assess whether DeFelice’s work stands the test of replicability, meaning whether other scientists can confirm her findings.
The bottom line
Infertility is a complicated issue. A large web of possible causes and interactions make the situation more complex. Often, healing from infertility involves not just one solution, but many. These solutions might include light elimination therapy, bioidentical hormones, targeted nutrition, or the use of certain vitamins and supplements.
In a Fertility Friday podcast episode, Joy DeFelice noted that the presence of light during sleep may not always be the problem behind infertility. Still, considering how much more artificial light we as a society have added to our daily life (and our night life, too), LET might help many women improve their fertility, increase their chances of healthy pregnancies, and regulate their cycles. It is easy, cost-effective, non-invasive, and simple. Women and couples struggling with infertility certainly have nothing to lose, and something very precious to potentially gain, by giving it a try.
 Barron, Mary. “Light Exposure, Melatonin Secretion, and Menstrual Cycle Parameters: An Integrative Review.” Biological research for nursing, vol.9 (2007): pp. 49-69. 10.1177/1099800407303337.
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