New Zealand Listener - October 13, 2018

34 LISTENER OCTOBER 13 2018

by Nicky Pellegrino

HEALTH

ThisLife

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S

ome of us are naturally morning people,

bouncing out of bed first thing, whereas

others are night owls and prefer to stay

up late. The time we feel most alert or

sleepy is linked to the body’s chrono-

type – its inner biological clock. To

some extent, this is down to our genes,

although other factors also play a part.

“Your chronotype is how early or late you are

compared with everyone else,” says Céline Vetter,

a circadian sleep specialist from the

University of Colorado Boulder. “In

modern societies, there is quite a

spread. We’ve created an environ-

ment that is very different to the one

our circadian system evolved with.

We spend most of our days inside,

so have low exposure to light during

the day, and then we lighten up our

nights.”

There is evidence that chronotype

can influence health. Night owls have

higher rates of obesity, high blood pressure and car-

diovascular disease, for instance, as well as a greater

chance of suffering depression than early birds.

Vetter’s most recent research looked at data

from an ongoing US project, the Nurses’ Health

Study II. She followed more than 32,000 middle-

aged women who were depression-free at baseline,

in 2009, to see whether

they were diagnosed

with depression or

experienced symptoms.

After accounting for

other possible modify-

ing factors, Vetter found

the early birds had a

12-27% lower risk of depression com-

pared with those who identified as

intermediate types. Meanwhile, night

owls had a 6% higher risk than the

intermediates.

Although those numbers aren’t

huge, Vetter believes they are

significant from a prevention

perspective.

“Some rare people are extremely

early or late – that is a familial genetic

condition – but most of us can

adapt,” she says. “You travel across

time zones and adapt, for instance.”

Any change may need to be

gradual, so the way to become an ear-

lier riser is to advance the alarm clock

a little over a period of several weeks.

And your natural chronotype may be

stubborn at first.

“But being an early type seems to

be beneficial, and you can influence

Tr ic k s of

the light

Being a night owl may be

bad for your health but

exposure to daylight can

turn you into an early bird.

NUTRITION • FOOD • WINE • PSYCHOLOGY • SPORT

Circadian sleep specialist

Céline Vetter.