As the days get shorter in the northern hemisphere over the coming weeks, lack of sufficient daytime light exposure due in part to Covid-related isolation is going to cause the mental well-being of many millions of people further deteriorate.

That’s on top of other significant stressors here in the U.S. like the millions of “what-ifs” related to the aftermath of the election. But Seasonal Affective Disorder (SAD) is predictable, and easily treatable. People just need to be aware of it & know what to do if it happens.

Basically, we don’t function all that well as humans with a day length that changes throughout the year, because diminished sunlight exposure in winter messes with our biological (circadian) clocks. And the results can pile on other stressors that bring people down.

There are ways to ward this off. Get bright light exposure within the first half-hour of waking in the morning. That may well have to be by artificial means in the dead of winter. That early light is the signal that reminds your biology what time it is in the “circadian day”.

If the weather is good, try to spend more time outdoors during the day getting direct sunlight exposure. If that’s not possible, try running “daylight”-colored lamps indoors (but only during the daytime!) At night, use only warm colored light to reduce sleep interference.

And try to get sufficient sleep as consistently as possible. Good “sleep hygiene” has many known health benefits beyond helping to regulate mood. But remember in all of this that the timing of light exposure is key to ensuring a regular sleep/wake rhythm in winter.

Besides, more sleep of better quality supports a healthy immune system. And we’re all going to need solid immune responses this winter to fight off the double onslaught of Covid *and* seasonal flu. To have a decent chance, get more sleep.

I’m concerned that a lot of people are already in a fragile mental state right now, whether they realize it or not. 2020 has been devastating to global public physical and mental health. A long, deadly winter could push some people over the edge. It will be a critical time.

So be good to yourselves and each other this winter. Bright “cool” light in the morning and day, dimmer “warm” light in the evening, and darkness for sleep overnight. Exercise. Eat well. Stay hopeful. Hold those you love a little closer.

Thank you for coming to my TED talk.