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For some, winter is a wonderful season, full of holiday cheer, gorgeous snowy views, and activities like sledding and skiing. But for others, the season only brings the blues. Their mood takes a dip in the fall and winter even when life is otherwise going well.
Is it winter blues or seasonal affective disorder (SAD)?
For about 3 percent of people, this mood downturn is so severe that they have something called seasonal affective disorder (SAD). They not only feel blue but they also experience:
- Loss of interest in things they usually like
- Unusual tiredness or sluggishness
- Difficulty sleeping
- A tendency to overeat and gain weight
- An inability to concentrate
- Feelings of hopelessness, or sometimes even having suicidal thoughts
What is it about the colder months that brings about the blues? Is there a way to beat it?
The secret may lie in a free resource we’re all familiar with—light! Plants rely on soaking up light to make food and grow, but it turns out that we animals need light, too. Our biology is so wrapped up with light that our metabolism, mood, and thinking are all affected by it.
Our mood is intimately tied to light
The winter blues and SAD don’t just happen to people because winter is their least favorite season. There is actually a biological reason for winter depression. The people most susceptible to winter-induced depression are those living far from the equator. Living farther away from the equator means you get fewer daylight hours in the wintertime.
Because there's less daylight during fall and winter, the body’s circadian rhythm gets disrupted. When it comes to tuning our body clock, light is all-powerful—with less and less of it during fall and winter, our body’s natural rhythms weaken, which is bad for our mood, metabolism, and cognitive abilities. It’s also possible that less sunlight leads to a drop in serotonin, a brain chemical that's important for regulating mood.
Artificial light can boost mood and keep winter blues at bay
Now, to bring the mood up a bit. By artificially adding light into our lives, we can actually go head-to-head with the winter blues! Numerous studies have shown that something as simple as using a lightbox can decrease symptoms of SAD. Ideally, you’ll want a full spectrum light source, such as a lightbox designed for this treatment. But even a very bright bulb from the hardware store can help.
Typical treatment involves using the light for about 30 minutes each morning if it has a brightness level of 10,000 lux, or for about one to two hours if it has a brightness level of 2500 lux. For comparison, 10,000 lux is on the low end of ambient daylight, whereas an overcast day is about 1000 lux.
Don’t stare directly into the light—that’ll hurt your eyes. Instead, have it offset about 30 degrees from your gaze and about two feet away. You can have your coffee, scroll through the news, or enjoy a morning podcast while you have your lightbox on.
Bright light therapy improves your mood by regulating your circadian rhythms and increasing serotonin. What’s especially great about this treatment is that it can be easily combined with medications or other treatments without interfering or introducing side effects. Even for those with year-round depression, bright light therapy (combined with taking an antidepressant) can provide an extra mood boost.
Bright light therapy can also help with sleep and daytime fatigue
Bright light therapy may have even more of a direct effect on our sleep. Often, those with depression (especially seasonal depression) also have later chronotypes, meaning that they are biologically wired to want to sleep and wake later than the average person. This makes for a double whammy in the winter—they have both a depressed mood and a harder time getting up in the morning.
But doing bright light therapy immediately upon waking can help to shift night owls’ biological clocks earlier, improving their quality of sleep at night and impacting how alert and refreshed they feel in the morning.
Bright light doesn’t just help night owls to perk up during the day and sleep well at night. For those with chronic illnesses like Parkinson’s disease and Alzheimer’s dementia, and for those recovering from illnesses like cancer, bright light therapy helps to reduce fatigue throughout the day. For these patients, light therapy might be particularly welcome news because it's a way to treat symptoms without adding more drugs to their regimen.
Too much of a good thing (at the wrong time) can be counter-productive
Now that I’ve touted the magical properties of light, you might be thinking you should be exposed whenever you can. Not so fast—timing is actually crucial for light therapy.
Light is the strongest tuner in our body clocks. It tells our master clock, the suprachiasmatic nucleus, what time it is in the 24-hour cycle. That means light at the wrong times can have exactly the wrong effect. For example, using screens in the evening can disrupt sleep by making a person more alert at bedtime, which means they could have a harder time falling asleep or getting into a deep sleep.
Sleep isn’t the only thing affected by light at night. Too much brightness in the evening might contribute to depression symptoms, too. One study found elderly people who were depressed were more likely to have brighter environments at night. This was true even after the scientists accounted for sleep, physical activity, and other health factors that might affect depression.
Don’t feel like you have to hide your screens after sunset, though. It turns out that not all wavelengths of light affect our brains the same way. Shorter wavelengths like blue light stimulate the brain’s master circadian clock, while longer wavelengths like red and orange lights do not. That’s why our cavemen ancestors’ body clocks were not disrupted by their evening campfires.
To mimic the campfire effect, you can turn your phone or tablet screen to night mode, which is dimmer and more orange. You can also wear blue-light-blocking glasses, which are spacey-looking glasses that filter out the shorter wavelengths that affect your circadian clock. But make sure you don’t wear them during the day—that’s the time you do want bright lights to come through.
A version of this post, titled How to Harness Light to Defeat the Winter Blues, also appears on Quick and Dirty Tips.
