We talk constantly about light.
Get outside.
See the sunrise.
Stop staring at screens.
Get morning light in your eyes.
All of which I care about.
But I think we forget something:
darkness is also biological information.
It isn't just the absence of the useful thing.
It is a signal of its own.
Your body needs contrast
Day means something partly because night means something different.
Bright means something because dark exists.
Warm seasons mean something because cold seasons exist.
Biology is full of contrast.
And increasingly, modern life is removing it.
We live in:
warm houses all winter
cool houses all summer
bright rooms at midnight
dark rooms at noon
the same food in every season
the same temperature every day
We have made the environment incredibly flat.
Convenient.
But flat.
Darkness tells the body something
As environmental light falls in the evening, your circadian system receives information that the day is ending.
Melatonin production rises.
Body temperature shifts.
Sleep pressure changes.
Repair processes move into a different phase.
The whole organism begins transitioning.
Darkness isn't a passive condition.
It is part of the timing system.
Which makes winter more interesting
I used to think of winter mostly as:
less sunlight.
Something to survive until May.
Now I think about it differently.
In the north, winter also gives us long darkness.
And maybe that is part of what the season is for.
A period with:
longer nights
less environmental light
more sleep opportunity
cold
slower growth
less abundance
We are very good at asking:
How do I replace summer in February?
Maybe another useful question is:
What is winter trying to give me that summer cannot?
Melatonin is one of the obvious answers
Melatonin gets reduced to:
the sleep hormone.
Take a pill.
Pass out.
But melatonin is much more deeply involved in circadian timing and cellular biology than that framing suggests.
And your own melatonin rhythm is intimately connected to light and darkness.
Which makes protecting darkness feel more important to me than simply swallowing synthetic nighttime.
I want the signal.
Not just the pill.
Modern nighttime isn't very dark
This part is easy to forget because we're accustomed to it.
Kitchen lights.
Bathroom lights.
Television.
Phones.
Street lights.
Night lights.
Appliance LEDs.
A bright house at 9 p.m. doesn't feel bright anymore because it is normal.
But biologically it is still light arriving at a time when our ancestors would have had:
fire
moonlight
stars
darkness
Very different spectrum.
Very different intensity.
I don't think every photon after sunset is a crisis
This is where health culture gets ridiculous.
You should be able to live.
Have dinner.
Read.
Talk to your family.
You do not need to sprint through your house at sunset wearing welding goggles because somebody told you one LED will destroy your mitochondria.
But I think the overall direction matters.
Bright morning.
Bright day.
Dim evening.
Dark night.
Contrast.
We use candles a lot in winter
This is one of my favourite seasonal shifts.
Breakfast before sunrise?
Candles.
Dinner when it's already pitch black?
Candles.
Bath?
Candle.
The point isn't that a beeswax candle has some mystical purity that makes electricity evil.
It's that the environment feels unmistakably different at night.
Warm.
Dim.
Low.
Dark around the edges.
Your nervous system does not have to wonder whether it is 1 p.m.
And then actually sleep in darkness
This is probably the least glamorous health advice available.
Dark bedroom.
No glowing television.
No phone beside your face.
No bathroom lit like an operating room at 2 a.m.
Just dark.
I think we spend enormous amounts of money optimizing sleep while ignoring one of the fundamental environmental instructions for sleep.
Night.
I think this matters for skin too
Skin has circadian biology.
Barrier function, cell activity and repair processes change across the day-night cycle.
So when I say I think about light for skin, I don't only mean:
get sun.
I mean:
give the organism a coherent day.
And then give it a coherent night.
This is one reason I don't panic about winter the way I used to
Yes, I want the daylight that exists.
I want to see morning light.
I want to get outside.
I want cold.
I want every useful photon the season offers.
But I also don't think we're necessarily supposed to reproduce July indoors for five months.
Winter gives us something summer doesn't:
a lot of dark.
Maybe the answer isn't always fighting it.
Maybe some of the adaptation is letting the season actually be the season.
Earlier dinners.
Lower lights.
Longer evenings.
More sleep.
Less stimulation.
Dark bedrooms.
Cold outside.
Warm food.
Then spring comes back.
Light is an input.
So is darkness.
And I think health gets considerably more interesting once you stop treating one half of the cycle like nothing.