SAN FRANCISCO — Are “extreme” early birds really so extreme? A new study by researchers at the University of California San Francisco (UCSF) finds that the rare body clock function of some people that allows them to go to sleep at 8 p.m. and get back up at 4 a.m. may not be as rare as previously thought.
This body clock quirk, called advanced sleep phase, appears in at least one in 300 adults, according to the UCSF study. People who meet this condition typically fall asleep before 8:30 p.m. and wake up on their own before 5:30 a.m., that is, without work or other engagements dictating their wake-up time. Advanced sleepers tend to show this pattern before they’re 30, and don’t use any sleep aids or medications to assist in their sleeping or rising habits.
Simply put, extreme early birds are able to get up and fall asleep earlier completely on their own.
The body’s clock, also known as its circadian rhythm, operates by releasing the sleep hormone melatonin at certain times. Those with advanced sleep phase have a premature release of melatonin and a shift in body temperature. This condition is different from the pattern of waking up earlier as one ages, as well as the phenomenon of waking up in the middle of the night in depressed people.
“While most people struggle with getting out of bed at 4 or 5 a.m., people with advanced sleep phase wake up naturally at this time, rested and ready to take on the day,” said study senior author Dr. Louis Ptacek, professor of neurology at the UCSF School of Medicine, in a media release. “These extreme early birds tend to function well in the daytime but may have trouble staying awake for social commitments in the evening.”
Dr. Ptacek and his colleagues at the University of Utah and the University of Wisconsin calculated the prevalence of advanced sleepers using data from patients at a sleep disorder clinic over a nine-year period. They examined 2,422 patients, of which 1,748 had symptoms of obstructive sleep apnea, which the researchers found was unrelated to sleep-cycle hours. Participants were surveyed about their sleeping habits and medical histories, and provided saliva samples to measure melatonin levels. They also had their brainwaves, oxygen levels in the blood, heart rate, and breathing measured as they slept.
Of this group, 12 met the criteria for advanced sleep phase. Four of those declined enrollment in the study, leaving eight, or 0.03 percent of the total number of patients — one in 300 people. Because four people chose not to participate, the researchers say their figure is a conservative one. Interestingly, the authors found that all eight advanced sleepers had an immediate family member who were also extreme early birds, which indicates familial advanced sleep phase.
Not surprisingly, researchers say that it’s night owls who tend to struggle more with sleeping problems that impact their health and productivity.
“Generally, we find that it’s the people with delayed sleep phase – those night owls that can’t sleep until as late as 7 a.m. – who are more likely to visit a sleep clinic. They have trouble getting up for work and frequently deal with chronic sleep deprivation,” says Ptacek. “We hope the results of this study will not only raise awareness of advanced sleep phase and familial advanced sleep phase, but also help identify the circadian clock genes and any medical conditions that they may influence.”
The study is published in the journal SLEEP.