If pregnancy is in your near future, and you have been surfing the web for all things related to pregnancy, you may have come across the term “lunaception.” Lunaception is the belief that your menstrual cycles are meant to follow the cycles of the moon. If you can get your menstrual cycles in sync with the lunar cycles, your will get your hormones in balance, and be able to predict when you are most fertile. Over time, you will know when you should have sex if you want to get pregnant and when to avoid sex if you want to avoid pregnancy. [1,2]
The idea that menstruation, ovulation, and the phases of the moon are linked is not new. [1,2,3,4] The average menstrual cycle is 28 to 32 days.  A complete lunar cycle is 29.5 days.  To understand lunaception, you need to start with a basic understanding of the moon’s phases: 
- The lunar cycle begins with the new moon. During this phase, the moon is completely dark.
- The next phase is the waxing crescent. During this phase, the moon is seen as a crescent.
- Then comes the first quarter, during which we see half the moon.
- Next is the waxing gibbous, during which we see more than half the moon.
- In the middle of the lunar cycle, we see the full moon.
- The moon then goes through the waning phases of gibbous, last quarter, crescent, and darkness.
What Lunaception Says
The term “lunaception” was developed by Louise Lacey in her book Lunaception. The book appeared back in the late 1960’s. She proposed that during the evolution of humankind, the world was only in full light at night during the full moon, the middle of the lunar cycle. [1,2]
According to her theory, women are meant to start menstruating during the new moon, when the night sky is dark. The light of the full moon should trigger ovulation in the middle of the lunar cycle. We know that most women ovulate between 13 to 20 days after the start of their menstrual period. If menstruation starts at new moon, this roughly corresponds to the middle of the lunar cycle and the full moon. [1,2]
For a woman to get her menstrual cycle under lunar control, she should sleep in total darkness except for the the middle of the month – days 14 and 15 – when she sleeps with a 15 to 25 watt, white nightlight. Over a period of 6 -12 months, lunar cycle and menstrual cycle will start to merge. According to the lunaception plan, a woman will then be in natural rhythm and be able to control pregnancy by planning sex around more natural ovulation. [1,2]
Does Lunaception Work?
Even Lacey admits that there are no studies to back up lunaception, but there are plenty of women who have found it to be the real deal, at least for them. Several years after publication, Lacey’s book and her theory were hard to find. The book actually went out of print for a while. But there has been a resurgence of interest on the web and the book is now back, along with a website. 
One large study is mentioned as partially supporting the theory of lunaception. Back in 1986, a study done among 826 female volunteers found that a significant proportion of women actually did have menstrual cycles that began during the new moon. Over 28 percent of women were lunar-synched. No other times of the lunar cycle approached this constancy. This study suggest s that there really is some natural tendency for the menstrual cycle to follow the lunar cycle. 
Other studies in humans have linked the lunar cycle to hospital admissions, heart attacks, accidents, suicides, and crime. Animal studies have found a lunar link to sexual development in insects, hormone production in fish, bird migration, and immune response in mice. Although these links are not well understood, they may involve the brain hormone melatonin. This hormone helps regulate rhythmic activities of the body like sleep, appetite, and the onset of puberty. Melatonin secretion occurs in darkness and is inhibited by light. [2,3,4]
Long story short, it’s not that farfetched to believe the lunar cycle helps coordinate a whole range of rhythmic body functions. Ovulation and menstrual cycles may be included. [2,3,4]
Should You Try Lunaception?
Lacey claims that the normal relationship of menstrual cycles to lunar cycles has been thrown out of whack by birth control pills, stress, streetlights, cars, and noise. We no longer live in a world lit only by candles and the moon. 
The lunaception method includes other ways of tracking ovulation, like taking your temperature and checking your cervical mucous. This adds some weight to the method.  These are tried and true tools of fertility awareness. Your temperature ticks up slightly after ovulation and your cervical mucous starts to looks like egg white 1 -2 days before ovulation. 
To sleep in darkness, you really need to make your room dark. You should not be able to see your hand in front of your face when the lights are out. Lacey suggests using a red night light in your hallway or bathroom, if you need to get out of bed. The red light is closer to the firelight that would have lit the ancient world, as opposed to a bright white light that might trigger ovulation too soon. 
The bottom line on lunaception is that it might work. It might help you use the rhythm method of birth control, especially if you combine it with traditional fertility awareness of temperature and cervical mucous monitoring. There is no real danger, other than your or your sleeping partner tripping over or bumping into things in your totally dark bedroom. If you are intrigued by lunaception, you can get started by visiting the lunaception website at http://lunaception.net/.
- The Weston A. Price Foundation, Fertility Awareness, Food, and Night-Lighting.
- Biology Online, The lunar cycle: Effects on human and animal behavior and physiology.
- Acta Obstetricia Et Ginecologica Scandanavica, The regulation of menstrual cycle and its relationship to the moon.
- American Pregnancy Association, Fertility Awareness: Natural Family Planning (NFP).
- NASA, What are the phases of the Moon?