Casanova isn’t typically thought of for his ingenuity. But back in his days of sexual conquests, the great lover reportedly found a new way to use a lemon rind: as a predecessor to the cervical cap. Aside from oils suggested by Ancient Greece and the pull-out method, this was one of the earliest known forms of female contraception. Other iterations followed (including a popular method in the mid-1800s which involved an injection of water, salt and vinegar into the uterus), but incremental improvements weren’t notable, let alone effective. That is, until October 15, 1951, when chemist Carl Djerassi invented a synthetic chemical called norethindrone that would become the basis of oral contraceptives and the birth control revolution.
Today, 67 percent of women in the U.S. use hormonal contraceptives, according to the Guttmacher Institute. The most obvious reason for taking birth control, of course, is to prevent pregnancy. But it can also help treat health issues including menstrual cycle-related symptoms, acne, polycystic ovary syndrome and endometriosis.
The most ubiquitous form of hormonal contraception are birth control pills — you know, the one so popular it’s known as simply “the pill.” Most pills are “combined oral contraceptives,” meaning they contain synthetic forms of two hormones: estrogen and progesterone (often called progestin). Some pills, however, only contain one hormone. Modern contraception, of course, is not limited to pills alone: The past decade has seen the emergence of patches, injections, implants and vaginal rings.
Hormonal birth control works by modifying reproductive functions. As is usually the case when we alter the body’s natural processes, birth control can come with side effects. Nausea, weight and period fluctuations and mood changes are the most common. However, some research has determined some possible links to increased risk of breast and cervical cancers.
Sleep difficulties aren’t typically listed as a symptom of birth control. But given the role hormones play in regulating our sleep cycles, it’s reasonable to wonder if tinkering with them affects our rest.
First, it must be stated that, as with most stories involving sleep and science, the research on birth control and rest amounts to a mixed collage of conflicting information. In this case, we can attribute the gray area to a few issues. One, there isn’t enough research. Two, the subject matter comes with inherent limitations. Why? Well, partly because designing experiments gets tricky — it’s hard to identify a control group given how widely reproductive cycles vary. Plus, chemical composition varies across different birth control pills.
The 28-day menstrual cycle involves four main hormones: estrogen, progesterone, follicle stimulating hormones (FSH), luteinizing hormone (LH), estrogen and progesterone. And it consists of four phases.
First up is menstruation, when non-pregnant women shed their endometrial linings. Then comes the follicular phase, which is basically five days of ovulation prep. The brain’s hypothalamus sparks production of (FSH) and (LH), which find their way to the ovaries. Working together, the duo stimulates the growth of follicles (encased eggs). They also cause an uptick in estrogen, which in turn makes FSH levels fall. All the hormone fluctuations set the scene for one follicle to emerge as dominant, leaving the rest to shrivel and die. Survival of the fittest starts early.
Time for ovulation. High estrogen levels spark an increase in LH and the dominant follicle releases an egg into the fallopian tube. At the same time, cervical mucus thickens because only thick mucus can catch sperm, and send that lucky swimmer to fertilize the dominant egg.
During the final, two-week-long luteal phase, a woman can officially declare herself pregnant — that is, if the sperm and egg become one and get implanted in the uterus. If no egg is fertilized, we’re back to menstruation.
How does birth control alter the menstrual cycle to prevent pregnancy? Well, combined pills (estrogen and progesterone) suppress two processes: ovulation and cervical mucus thickening. Suppressing ovulation hinges on suppressing the release of hormones called gonadotropins. Progesterone-only pills (e.g., Yaz) primarily work by keeping cervical mucus thin and unable to catch sperm.
While the connection between sleep and sex hormones still isn’t entirely clear, research indicates some natural correlation between menstrual and sleep quality. In a 2004 study led by sleep researcher Fiona Baker, Senior Program Director of Human Sleep Research at SRI International, women reported sleeping worse during the premenstrual phase and during the menstrual cycle. However, they didn’t have issues falling or staying asleep.
In some cases, birth control hormonal disruption can prove curative, especially for women with menstrual irregularities. Researchers at the Puerto Rico University School of Medicine investigated the case of an 18-year-old with a rare condition called menstrual-related hypersomnia (MRH) and found that oral contraceptives actually relieved her symptoms.
Another study, led by Brazilian sleep researcher Helena Hachul, used a battery of sleep tests, collectively called polysomnography (PSG), to monitor the rest of 931 women who’d reported disturbed sleep. Hachu found that women using hormonal contraceptives actually slept better, snored less and and had more REM sleep than women on no contraceptives. Menopausal women and premenopausal women with irregular menstrual cycles reported the greatest incidence of sleep disturbances.
In another fascinating study from 2007, Hachul studied nearly 300 premenopausal women in Sao Paulo, Brazil. She found that those taking hormonal contraceptives slept more efficiently than women who weren’t on birth control.
A team led by Susan Brown at the University of Hawaii Hilo compared birth-control free women with those taking oral contraceptives or Depo Provera over the course of a year. Participants on Depo Provera reported worse sleep and lower wellbeing than their au-naturel counterparts. Additionally, women with irregular cycles were twice more likely to report difficulty sleeping.
But results vary wildly. For instance, studies on female rats found that estradiol, an estrogen synthetic often used in oral contraceptives, suppressed REM sleep. These findings seem to carry over into humans: A study from Universidade Federal de Sao Paulo, Brazil compared women taking combined oral contraceptives with those using topical azelaic acid to treat acne Compared to the azelaic group, oral-contraceptive group had higher levels of cortisol, aka the “stress hormone,” which can impair sleep.
So what does all this mean? Does birth control affect sleep positively? Negatively? At all? The answer is: It depends. In the case of women already struggling with irregular menstruation-related sleep problems, better sleep could actually be another benefit of the pill. However, the chemical makeup of different birth control pills, combined with the biological makeup of the women taking them, introduce enough unknowns into the mix to merit further research.And with two-thirds of American women taking birth control pills, future investigations of the pill-sleep relationship is more than welcome — it’s necessary.