By Dimitri Ehrlich
Vampires and Keith Richards not withstanding, our bodies were made to sleep at night. This is why humans never evolved adaptations that many nocturnal animals have, such as night vision. Most of us know about circadian rhythms and are at least vaguely aware that they play an important role in regulating our sleep cycles. They run on 24-hour cycles and help regulate our inner clock, signaling when we should wake up, when we should go to sleep and much more. Circadian rhythms are molecular “clocks” that synchronize physiology with environment, affecting not only our sleep schedule, but also fluctuations in appetite, body temperature, hormone levels, alertness and blood pressure, in addition to regulating our digestive and endocrine systems.
But it’s less well-known that circadian rhythms are just one of four biological rhythms that regulate the human body’s natural cycle of processes. There are also diurnal rhythms, which sync with day and night; ultradian rhythms, which occur over a shorter period of time, several times a day; and infradian rhythms, which last more than 24 hours (such as a menstrual cycle).
Together, these four interconnected processes are like a master clock, controlling all of the body’s major chemical functions. Our biological rhythms are an astonishing feat of evolution, a symphony of thousands of nerve cells acting in concert to synchronize the complex miracle of human life. But when these natural biological rhythms are disturbed, we may experience disorders including insomnia and depression. One common but short-term example of this is jet lag: When we change multiple time zones on a plane, we disrupt our circadian rhythms. Similarly, a lack of exposure to sunlight can result in seasonal affective disorder, with its rather apt-sounding acronym: SAD. And anyone who has ever had to work a night shift (or even just pull an all-nighter) knows how painful sleep deprivation can be. It can also lead to a lack of alertness with serious consequences: Both the Chernobyl disaster and the Three Mile Island accident occurred during night shifts. Biological rhythm disorders can cause anxiety and depression, and can even increase your risk of serious illnesses such as diabetes and obesity.
While we can’t entirely control our biological rhythms, we can take common sense steps to avoid disrupting them. These include exposure to natural light, especially early in the day, following a consistent sleep schedule, exercising, avoiding excessive caffeine consumption and limiting screen time before bed. As for infradian rhythms, many are specific to women and while more research is still being done, changes are already afoot. For example, the U.S. women’s soccer team now has a training regimen that takes infradian rhythms into account.
“Infradian rhythms, such as during menstrual cycles, profoundly impact women’s cortisol levels, metabolic rates, immunity, microbiome, mood and much more,” says Minal Vazirani, MD, a triple board-certified physician who practices personalized medicine, with a primarily female patient base. “A customized approach that takes daily, monthly and seasonal rhythms into account is often overlooked in the traditional medical model.”
Vazirani—who is also a yoga teacher, Reiki master and medical director of Integrative Health & Wellness Associates in Warren, New Jersey—says, “As we integrate Mother Nature’s sage wisdom from ancient Ayurvedic medicine with modern functional medicine by taking into account each individual’s unique chronobiology, we can customize meal plans, intermittent-fasting regimens, lifestyle and exercise recommendations to support better outcomes and improved quality of life.”