Neurologists Pinpoint Which Strange Sleeping Patterns Run in the Family

"Having our behavior out of sync with our biology, we know that’s not good."

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Somewhere out there, there are people who naturally rise between 4 and 5 a.m., don’t crave more than 10 minutes of extra sleep on the weekends, and despite feeling a little drowsy during nighttime events, are thriving in their 9-to-5 workday. According to research released in the journal Sleep on Tuesday, these elite sleepers are not as rare as we once thought, and they may have their genes to thank for their sleeping habits.

This study’s lead author, Dr. Louis Ptacek of the University of California San Francisco, researches the genetics of circadian rhythm — the 24-hour cycles that govern a whole range of processes in the body, such as when you feel tired or hungry. In 1999, Ptacek first learned of 29 people in three different families who had strange, naturally early rising habits. But his most recent study shows that people with these fringe circadian rhythms that drive them to wake up extremely early are more common than he thought they were.

Based on his most recent work, he estimates that one in every 300 people might have the genetic markers of “advanced sleep phase” (ASP), which means they’re extremely early birds. He estimates that one in every 475 people has familial advanced sleep phase (FASP), which means that the genes for ASP run in the family.

“What we show in this paper is when we look at the very strongest morning larks, it tends to be familial,” Ptacek tells Inverse.

sleep, awake,
The tendency to naturally wake up extremely early may run in families. 

What Is It Like Being an Extreme Morning Lark?

As we get older, most people start to rise earlier, says Ptacek. But in this study, the team only evaluated people who started naturally rising in the early morning (between 3 and 5 a.m.) before the age of 30, which makes them more likely to have FASP. To establish who might be an extreme morning lark they recommend asking two questions:

  • On a long weekend or vacation with few or no responsibilities or obligations when would you go to bed?
  • On a long weekend or vacation with few or no responsibilities or obligations, when is your final awakening for the night?

Those extreme early birds, on average, stuck to rigid sleep schedules on both weekdays and weekends, and they reported feeling more awake when they first woke up. On the weekends, they only slept in for between five and 10 minutes. By comparison, “conventional chronotype” (normal sleepers) usually sleep in between 30 and 38 minutes on average on the weekends.

In a population of 2,422 people who sought treatment at sleep clinic, he identified 12 of these extreme early birds who met the requirements for ASP. Five of them, he explains met the criteria for FASP. All of them had first-degree family members who kept the same hours.

Some of these ultimate early risers thrive on those extra hours. Ptacek describes one “very successful businessman” who was part of a morning lark family. “He feels virtuous for getting up early in the morning and getting a lot of work done before you or I wake up,” says Ptacek.

sleep
There could be genetic components to "night owl-ness" too, which is when people struggle to fall asleep before the early hours of the morning. They often report worse sleep than the extreme early birds do. 

But not everyone feels invigorated by the morning lark lifestyle. One female member of the “succcessful businessman’s” family, described those hours as “cold, dark and lonely.” In the paper, the authors caution that extreme morning larks could end up with less sleeping hours because they try to stay up past their natural bedtimes for social, work, or family obligations — so it can be a double-edged sword.

Still, compared to the night owls of the world, Ptacek notes that the morning larks have it far better.

Morning Larks Versus Night Owls

The opposite of these advanced morning larks are night owls who sometimes struggle to fall asleep before the early morning hours. These findings show that being an extreme morning lark runs in families, and there’s some evidence suggesting that it’s the same for night owls — though the team didn’t address that idea specifically in this paper.

Ptacek looks at circadian rhythm as a phenotype, the physical expression of a gene into a trait — brown eyes, for example, is a phenotype. “The more extreme a phenotype, whatever it is, the more likely it’s strongly genetic.” Some night owls may also fall on the extreme end, which suggests a strong genetic component. But Ptacek adds that night owls are a “messier” population to study for a few reasons that have to do more with society than with genetics.

For one, night owls tend to have many more sleep complaints and other disorders than morning larks do, because they’re often awakened far before their biological clock wants them to. We already know that living out of sync with our biological clocks can cause health problems based on studies done on night shift workers, who live and work during their biological nighttime. Studies on night shift workers note that they have higher risks of breast cancer and obesity. Night owls, like shift workers, are living out of sync with their natural rhythms.

“Having our behavior out of sync with our biology, we know that’s not good,” says Ptacek. “If we knew our biology and listened to our body clock, if we lived on that schedule, that would be the healthiest thing for all of us I think.”

Fortunately for morning larks, their strange biological rhythms fit seamlessly into the constraints of a 9-to-5 school or workday. So they may leave in the morning feeling particularly like a hustler, but some of them they may have their DNA to thank for their early rising habits.

Abstract:

Study Objectives: Report the first prevalence estimates of advanced sleep phase (ASP), familial advanced sleep phase (FASP), and advanced sleep–wake phase disorder (ASWPD). This can guide clinicians on the utility of screening for extreme chronotypes both for clinical decision-making and to flag prospective participants in the study of the genetics and biology of FASP.

Methods: Data on morning or evening sleep schedule preference (chronotype) were collected from 2422 new patients presenting to a North American sleep center more than 9.8 years. FASP was determined using a severity criterion that has previously identified dominant circadian mutations in humans. All patients were personally seen and evaluated by one of the authors (C.R.J.).

Results: Our results demonstrate an ASP prevalence of 0.33%, an FASP prevalence of 0.21%, and an ASWPD prevalence of at least 0.04%. Most cases of young-onset ASP were familial.

Conclusions: Among patients presenting to a sleep clinic, conservatively 1 out of every 300 patients will have ASP, 1 out of every 475 will have FASP, and 1 out of every 2500 will have ASWPD. This supports obtaining a routine circadian history and, for those with extreme chronotypes, obtaining a circadian family history. This can optimize treatment for evening sleepiness and early morning awakening and lead to additional circadian gene discovery. We hope these findings will lead to improved treatment options for a wide range of sleep and medical disorders in the future.