Days are getting shorter. Leaves are falling. That can only mean one thing: winter is on the way. And along for the ride are lethargy and depression.
Tens of millions of Americans suffer from the winter blues. A more severe version of the condition, known as seasonal affective disorder (SAD) or winter depression, affects around 5% of adults . Symptoms may include:
- low energy
- difficulty staying focused on tasks
- sleep and appetite issues
- feelings of hopelessness and worthlessness
In this article, I’m going to address what causes the winter blues and what you can do about it. If you are just interested in tools and tactics, skip directly to that section.
A matter of time and place
Depressive symptoms peak in the late fall and winter months. Just check out the Google search volume for seasonal affective disorder  over the past five years:
SAD searches peak yearly at the end of October and beginning of November. Search volume only starts to decline rapidly around the beginning of May.
Geography also plays a role in the winter blues. The farther from the equator, the more likely you are to be affected. Indeed, the top three states for searches are Alaska, Maine, and Vermont, while the lowest search volume comes from Florida, Texas, and Nevada:
Records of SAD patients back this up: only 1.4% of Florida’s population is diagnosed with the condition. That number jumps to 9.9% in Alaska .
Light’s role in winter depression
Looking at the Google search volume for LED lighting, we see a remarkably similar seasonal pattern :
People are thinking more about light in the winter. So perhaps light has something to do with SAD.
Let’s look at the duration of daylight on the winter solstice, December 21, 2018, in several cities :
- Miami, Florida: 10h 32m
- New York, New York: 9h 15m
- Seattle, Washington: 8h 25m
- Anchorage, Alaska: 5h 27m
Wow, no wonder so many Alaskans suffer from SAD! Consider that daylight at the equator lasts about 12 hours year-round. Even Floridians are getting a very short day in December.
Light has been shown to have a major influence on the winter blues. In the next section, I’ll go over exactly why.
Light and the circadian rhythm
Maybe you’ve heard of the circadian rhythm, otherwise known as the body clock. One of its main functions is to control the daily cycle of wake and sleep. When you wake up in the morning and feel tired in the evening, it’s because of the circadian rhythm.
Humans have a mechanism for detecting when it’s day and when it’s night. You’ve probably heard of rods and cones, but there’s actually another sensor in the eye that has nothing to do with vision.
Intrinsically photosensitive retinal ganglion cells, or ipRGCs, are only triggered by blue and blue-green light. Why blue? Think about it: our ancestors got plenty of light from the sun during the day, but there was very little light at night.
Very white daylight has a wide color spectrum that includes ample blue:
But fire is much dimmer, and it has a lot less blue:
When the ipRGCs are triggered by blue light, they send a signal to the body clock that “it is daytime.”
The issue is that the day is very short in the winter, so most of us don’t get enough daytime blue light. We go to work and come home in the dark. This doesn’t provide enough stimulus to synchronize the body clock.
But there’s an additional issue related to our modern lifestyles.
Electronics and lighting produce blue light
Just like the sun, the displays in our computers and phones, as well as the lighting in our homes, produce a lot of blue light. Just look at the spectrum of my smartphone:
Lighting at home can be equally blue-rich:
It’s fine, and actually desirable, to get blue light during the day. But when we continue to use most lighting and electronics at night, it provides a signal to the circadian rhythm that “it is still daytime,” even though it’s not.
These false signals disrupt our body clock and sleep patterns, exacerbating the symptoms of SAD.
Tools and tactics to combat the winter blues
To reduce the symptoms of winter depression, you want to focus on two things:
- Getting significant blue light in the morning and early afternoon
- Reducing blue light exposure in the evening
Thanks to some modern tools, you can combat SAD without living like a caveman.
Get significant blue light in the morning and early afternoon
If you have access to the outdoors, try to go for a 10–20 minute walk before noon. It can be chilly in the winter, but there’s no better daytime light source than natural sunlight.
If you feel a dip in the early afternoon, you can go for another short walk outside to combat the tired sensation.
Bright white therapy lamps
When natural sunlight is not an option or it’s just too cold outside, there are bright white therapy lamps* available from a number of manufacturers. Use these for 10–30 minutes in the same way you would get sunlight exposure.
It is advisable not to look directly at the light. You should turn the light off or move farther away from it if you experience eyestrain.
Reduce blue light exposure in the evening
There are two sources of significant blue light that can interrupt sleep:
- the screens on our phones and computers
- the lighting in our environment
Computers and phones
The easiest way to reduce blue light on your devices is to dim the display. Use your intuition: adjust the brightness to a level that’s comfortable for the time of day.
In addition, there are several apps that automatically turn your display orange at night. This has the dual benefit of reducing eyestrain and cutting down on sleep-interrupting blue light.
Just as dimming your phone and laptop screen reduces blue light, so does using a light dimmer. If you have dimmers for your existing lighting, turn everything down to a comfortable level in the final hours of the day.
Unfortunately, our research found that less than 5% of households have dimmers where they spend their evenings. Worse, dimmers can be expensive and difficult to install. We were determined to come up with a solution that would work well for most people.
Bedtime Bulb was designed to be the perfect evening light. It drastically reduces sleep-interrupting blue light while providing beautiful, comfortable illumination.
After measuring a number of light sources, we found Bedtime Bulb has the lowest circadian input of all (pay attention to the final column—lower is better):
Winter doesn’t have to mean winter blues
In this article, you learned how light has a major influence on the winter blues. To combat seasonal affective disorder:
- Increase exposure to blue-rich light in the morning and early afternoon
- Minimize exposure to blue light in the evening
By implementing the tools and tactics mentioned above, you may be able to create a more consistent circadian rhythm, enjoy higher quality sleep, and reduce the symptoms of SAD.
As we demonstrated, Bedtime Bulb is the perfect evening light: it’s bright enough for evening tasks, but it reduces sleep-distrubing blue light. It’s a great tool in the fight against the winter blues.
About the author
Greg Yeutter’s first word was “light.” For the last eight years, he’s been obsessed with light’s effects on health. Greg launched Bedtime Bulb as a simple, affordable solution to address unhealthy blue light at night.
 American Family Physician: Seasonal Affective Disorder
 Google Trends: seasonal affective disorder.
 Google Trends: LED lighting