Why am I more nocturnal than others I know?

If you’re still wide awake and full of energy when everyone in the house is sound asleep, it’s likely that biologically you are a “night owl.”

Sleep, like other body functions, is governed by our circadian rhythms, and the exact timings of an individual’s sleep/wake cycle vary from person to person. This variation is known as your “chronotype,” and it influences not only the timing of your sleep, but other daily activities, such as eating and exercise.

There are two main chronotypes: “early birds” and “night owls.” Early birds are early risers, functioning better in the mornings but ready for sleep relatively early; night owls rise later and take longer to reach peak functioning, but then remain alert until later into the night. Although there are extremes at either end of the scale, most people fall somewhere in between the two and are known as “intermediates.”

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GETTING THE MOST OUT OF YOUR CHRONOTYPE

A chronotype is genetically programmed—you can’t reset it. However, by understanding your chronotype, you can ensure you embrace rather than fight it. For instance, early birds may schedule important meetings for the morning and leave routine tasks for later in the day, when they are running out of mental steam. Happily, there is a growing trend for employers to recognize that not everybody performs best on a 9-to-5 schedule. Night owls benefit especially from more flexible working hours: one study found that allowing them to start work just half an hour later resulted in a significant drop in sick leave.

OWL OR BIRD?

Familiarity with your own sleep habits can help you adjust your lifestyle to better suit your chronotype. Try keeping a sleep journal and pay attention to the following indicators:

• Alertness on waking A good gauge of chronotype is how quickly your brain wakes up. If you repeatedly hit “snooze” or sleep through the alarm, you are likely more of a night owl.

• Focus and concentration Early birds peak early in the day, then concentration tails off gradually. Night owls start later but can retain their focus late into the evening and night.

• Physical performance Early birds peak physically in the morning; performing physical tasks or doing exercise at the optimum time for you will help you avoid injury and strains.

• Sleep time If they go to bed earlier than usual, early birds tend to fall asleep easily. For night owls, early nights are futile; it’s almost impossible for them to fall asleep before midnight.

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