Earlier this week, I reported on a recent study (Curtis et al., 2019) about extreme morning chronotypes often running in families and not being exceedingly rare (See, "Up and at 'Em: 4 A.M. Risers May Have Quirky Chronobiology.") Over the past few days, there's been a passionate (and somewhat heated) debate on the topic in the "comment" board for that post.

To my surprise, some readers read my posts as portraying advanced sleepers or extreme early birds as having a stigmatized "disorder." (Thankfully, one reader's comment addressed that misconception well.)

Source: Clipart

I reached out to the study's senior author, Louis Ptáček, to follow up on the sensitivity surrounding ASP being called a disorder. Ptáček is a professor of neurology at the UCSF Weill Institute for Neurosciences in San Francisco.

I actually happen to be an extreme "morning lark" who tends to fall asleep by 9 p.m. and wake up around 3:30 a.m., seven days a week. My ASP was a slight problem when my 11-year-old daughter was younger because I'd fall asleep while reading to her before bedtime. She'd still be wide awake, and I'd conk out, book in hand, until she nudged me. But everyone in my family has quirky chronobiology. I shared my familial history of circadian preferences and chronotypes with Ptáček in our email exchange:

"My mother and grandmother are both night owls; conversely, my father and grandfather were extreme early birds. Both my sisters are very productive night owls (who love to sleep in) and do their best thinking and creative work late at night. On the flip side, I have trouble staying up past 10 p.m. but "thrive" in the predawn hours and love my very-early-to-bed, very-early-to-rise routine."

Ptáček invited me and my family to participate in his research, which I'm excited about.

Q&A with Louis Ptáček About Extreme Chronotypes and Advanced Sleep Phase (ASP)

Christopher Bergland: In your recent paper (2019) about extreme morning chronotypes often being familial and not exceedingly rare, your team reported that about one in 300 people thrives on a very-early-to-bed, very-early-to-rise routine (e. ., going to bed at 8 p.m. and waking at 4 a.m.). Technically, you refer to these extreme early birds as having "advanced sleep phase" or ASP.

To the best of my knowledge, you don't use the acronym ASPD (with the "D" for "disorder"). Is there a reason you refer to extreme morning chronotypes using the acronym ASP, not ASPD?

Louis Ptáček: It is only a disorder if the person feels it’s an undesirable trait. (Some do.) We’ve now cloned many and identified genetic variants that lead to a strong genetic form of ASP (familial ASP; FASP). In the first family in which we cloned the first gene, one person felt it was a disorder (for her). She said, “[This disorder] wakes me up when it’s cold, dark, and .”

A relative who carries the same gene/variant as her feels virtuous for “being the early bird that gets the worm.” Many people in such families are indifferent to the trait and consider it neither negative nor positive: “That’s just how my family is.”

CB: Are there specific circumstances in which you would diagnose someone who functions best by going to sleep at 8 p.m. and waking up at 4 a.m. as having advanced sleep phase syndrome (ASPS), which most sleep experts seem to classify as a disorder?

LP: We’ve known forever that there are morning larks, night owls, and everything in between. When we first described FASP in 1999, the sleep disorders manual recognized ASPS, which is only diagnosed if the person complains about it. (There are many more out there who are morning larks and don’t complain about it. Because of ASPS, we termed the familial form ‘FASPS.’)

Since then, we’ve dropped "syndrome," as it does have negative connotations. Thus, we now call it FASP—and do not make any value judgments about chronotype. We should not discriminate against people because of skin color or or age or religion—and we should also not discriminate on the basis of chronotype!

CB: When your team analyzed each study participant's family history regarding circadian preferences, did you observe any hereditary patterns?

LP: Absolutely! Since we’re looking at the most extreme morning larks, our collection of study subjects and families is very enriched for families in which a single genetic variant in a single gene is causing FASP. [References below.]

When we engineer the genetic variants into mice, we have repeatedly recapitulated the early-to-bed/early-to-rise trait. Studies of these genes and mouse models are teaching us a lot about the regulation of human sleep.

Side note: The topic being discussed [here] is clock and chronotype. We also know that there is a large variation in the general population regarding how much sleep each person needs. There is a large range from natural short sleepers (NSS) to natural long sleepers (NLS), and there are stigmas associated with this, too.

I collaborate closely with a fantastic scientist named Ying-Hui Fu. [She’s a co-author on all the papers referenced below.] She described the first genetic form of NSS [in a 2009 Science paper], which we call familial natural short sleep—FNSS. We now have two more human sleep genes (with genetic variants causing FNSS) “in press.” This is going to be a great story, too!

Thanks to Louis Ptáček for his quick response and for helping all of us understand that ASP should only be considered a disorder "if the person feels it’s an undesirable trait."