Can you change your sleep schedule?
Here we see an early bird and
a night owl in their natural habitats.
The early bird rises with the sun,
springing out of bed abuzz with energy.
As the day goes on, they slowly get
more and more exhausted
until finally crashing around sunset.
Meanwhile, the night owl rises
long after the sun,
stumbling groggily from their bed.
After about 30 minutes—
or a cup of coffee—
they begin to come to life.
But they don’t really hit their stride
until later in the day,
at which point they comfortably
coast past sunset,
only heading to bed in the early hours
of the morning.
For many, this is a familiar story,
and one that’s easy to cast yourself in.
But how many people are truly
night owls or early birds?
And are our natural sleep schedules
predetermined at birth,
or can we change them?
The truth is there’s a lot of space
between these extremes,
and most people fall somewhere
in the middle.
These behaviors are determined
by our circadian system—
which is anchored by a pair
of nerve cell clusters
located in the anterior hypothalamus.
These nerve cells respond to light
exposure coming in through your eyes
to track the day-night cycle that dictates
your body’s internal clock,
or circadian rhythm.
That steady rhythm helps determine
the body’s flow of hormones,
with the broader circadian system
acting like a conductor
that keeps your organs functioning
in time with one another.
And a major part of that performance
is managing the body’s transitions
between being awake and being asleep.
Now, your circadian system can't just
decide its bedtime and knock you out.
However, by tracking how much
light you typically get
and when in your waking hours
you usually get it,
the system can make predictions about
when you’re likely to need sleep
and prepare your body accordingly.
For example, if you consistently
go to sleep around 10 pm,
your circadian system will start producing
sleep-inducing melatonin
around two hours before then
to tell your body it’s time for bed.
So if this rhythm is molded
by our sleep habits,
can we change it just by sticking
to a strict schedule?
To a degree.
Everyone’s bodies are unique,
so even two people with the same sleep
schedule might have different experiences
based on their circadian system’s
hormonal quirks.
For example, where early birds generally
flood with cortisol just before waking up,
night owls often have their cortisol peak
roughly 30 minutes after getting up.
Hormonal differences like these determine
how you experience your circadian rhythm.
And while these factors
can shift with age,
you’re unlikely to grow out of your body’s
preferred sleep schedule.
That said, you can cultivate habits
to help or hinder your circadian rhythm.
Keeping consistent sleeping hours helps
your body accurately predict
when to send out hormones,
making it easier to stick
to your schedule.
Conversely, research in sleep deprived
college students
has found their unpredictable
sleeping habits
weaken their entire circadian system.
Compromised circadian rhythms
are less effective
at coordinating organ functioning
and can incur health risks
like metabolic disorders
and vulnerable immune systems.
But perhaps just as important
as sleep hygiene is light hygiene.
Getting sufficient contrast between
bright daylight and dimmer nighttime light
is essential for synchronizing
your circadian rhythm,
and nothing establishes this contrast
better than sunlight.
Even on overcast days, sunlight is much
brighter than standard indoor lighting.
So if you're typically
awake during the day,
try getting outside as soon as possible
to teach your body
when to be active and alert.
It’s difficult to maintain
a sleep schedule
that pushes against your
body’s preferences.
And even if you succeed for months,
it only takes one bad night to send
your circadian system back to baseline.
But whether you’re an early bird,
night owl, or somewhere in between,
it’s important to remember
that as long as you’re consistent,
there’s no wrong time
to wake up or go to sleep.
What matters most is getting enough rest
for the day ahead.
