THE SUCCESSFUL ATTITUDE
ing until late afternoon or early evening.
Others of us are early chronotypes. They
rise easily and feel energized during the
day but wear out by evening. Some of us
are owls; others of us are larks.
You might have heard the “larks” and
“owls” terminology before. It offers a con-
venient shorthand for describing chrono-
types, two simple avian categories into
which we can group the personalities and
proclivities of our featherless species. But
the reality of chronotypes, as is often the
case with reality, is more nuanced.
The first systematic effort to measure
differences in humans’ internal clocks
came in 1976 when two scientists, one
Swedish and the other British, published a
19-question chronotype assessment. Sev-
eral years later, two chronobiologists—
Martha Merrow, an American, and Till
Roenneberg, a German—developed what
became an even more widely used assess-
ment, the Munich Chronotype Question-
naire (MCTQ), which distinguishes be-
tween people’s sleep patterns on “work
days” (when we usually must be awake by
a certain hour) and “free days” (when we
can awaken when we choose). People re-
spond to questions and then receive a nu-
merical score. For example, when I took
the MCTQ, I landed in the most common
category—a “slightly early type.”
However, Roenneberg, the world’s best-
known chronobiologist, has offered an
even easier way to determine one’s chro-
notype. In fact, you can do it right now.
Think about your behavior during “free
days”—days when you’re not required to
awaken at a specific time. Now answer
these three questions:- What time do you usually go to sleep?
- What time do you usually wake up?
- What is the middle of those two
times—that is, what is your mid-
point of sleep? (For instance, if
you typically fall asleep around
11:30 p.m. and wake up at 7:30 a.m.,
your midpoint is 3:30 a.m.)
Now find your position on the follow-
ing chart, which I’ve repurposed from
Roenneberg’s research.
Chances are, you are neither a com-
plete lark nor an utter owl, but some-
where in the middle—what I call a “third
bird.” Roenneberg and others have found
that “[s]leep and wake times show a near-
Gaussian (normal) distribution in a given
population.” That is, if you plot people’s
chronotypes on a graph, the result looks
like a bell curve. The one difference, as
you can see from the chart, is that extreme
owls outnumber extreme larks; owls have,
statistically if not physiologically, a longer
tail. But most people are neither larks nor
owls. According to research over several
decades and across different continents,
about 60% to 80% of us are third birds.
“It’s like feet,” Roenneberg says. “Some
people are born with big feet and some
with small feet, but most people are some-
where in the middle.”
Chronotypes are like feet in another
way, too. There’s not much we can do about
their size or shape. Genetics explains at
least half of the variability in chronotype,
suggesting that larks and owls are born,
not made. In fact, the when of one’s birth
plays a surprisingly powerful role. People
born in the fall or winter are more likely to
be larks; people born in the spring or sum-
mer are more likely to be owls.
After genetics, the most important fac-
tor in one’s chronotype is age. As parents
know and lament, young children are gen-
erally larks. They wake up early and buzz
around throughout the day but don’t
last very long beyond the early evening.
Around puberty, those larks begin mor-
phing into owls. They wake up later—at
least on free days—gain energy during the
late afternoon and evening, and fall asleep
well after their parents.
By some estimates, teenagers’ midpoint
of sleep is 6 a.m. or even 7 a.m., not exactly
in sync with most high school start times.
They reach their peak owliness around age
20 and then slowly return to larkiness
over the rest of their lives. The chrono-
types of men and women also differ, espe-
cially in the first halves of their lives. Men
tend toward eveningness, women toward
morningness. However, those sex differ-Morning
types also
tend to
be high in
positive
affect—
that is,
many are
as happy
as larks.