Every year, people across the globe spend billions of dollars trying to get a good night’s #sleep. In 2012, Americans spent over $32 billion alone on sleep-related products and interventions: sleeping pills, special mattresses and pillows, noise-cancelling machines, even sleep “consultants” making house calls.
Most of these interventions seek to change your behavior or alter your sleep environment. But what if all of these sleep solutions nothing more than snake oil? What if your sleep habits can’t be altered? What if sleep is something that is hard-wired into our genes? Is sleep nature or nurture?
Unsurprisingly, the answer is—it’s complicated. “Different individuals have different preferences for when they want to sleep and when they want to be awake,” says Dr. Anne-Marie Chang, a neuroscientist at Brigham and Women’s Hospital in Boston and a professor in behavioral health at Penn State. “We think that genetics plays a role in this.”
Dr. Chang’s work focuses on the workings of the circadian rhythms—our internal “biological clock” that helps determine our sleep-wake cycle. Dr. Chang and her colleagues contend that individual differences in circadian rhythms are at least partly genetically determined.
Dr. Chang’s work follows earlier findings about the link between genetics and sleep. The first clue that human sleep had a genetic component came about as a result of twin studies conducted in the 1930s. The studies showed that identical twins are more likely to sleep for similar amounts of time and even to go to sleep at similar times, than fraternal twins, who do not share as similar a genetic code.
Later research built on these findings. In the 1990s, it was established that a rare brain disease, fatal familial insomnia, was tied to a specific gene, further suggesting the genetic component to sleep. Research beginning in the early 2000s continued to demonstrate this link, especially focusing on the genetic causes of sleep disorders such as narcolepsy.
So what to think? Nature or nurture? Although this is often framed as a debate, most psychologists believe that the human condition is a result of a mix of environmental factors and our genetic heritage. “Sleep is a complex biological and behavioral state influenced by many factors, both genetic and environmental,” Dr. Chang says. “While we may have a preliminary understanding of a few of these factors, there is still much we do not know about how our genes and our environments shape our sleep.”
But it’s clear that whether you are an evening person or a morning person is at least in part determined by genetics. So, before buying that fancy new sleep machine or deluxe sleep-inducing mattress, you might want to check on how mom and dad slept at your age, or track down your long lost identical twin!