The leaves are starting to change, the days are getting shorter, the temperatures are dropping and the pumpkin spice euphoria of early September is starting to wear off.
If you find yourself feeling a little less cheerful than you were during spring’s transformation into summer, rest assured it’s not your imagination: There is a science-backed reason you’re more likely to feel down in the cooler months.
“It’s real,” Kathryn A. Roecklein, an associate professor in the department of psychology at University of Pittsburgh, told The Huffington Post.
The changes don’t necessarily affect everyone the same way, Roecklein added. But seasonal mood shifts often include less energy, feeling less social, losing interest in favorite activities, having cravings for carbs and changes in sleep ― either having trouble sleeping or wanting to sleep more than usual.
Scientists know there are a lot of biological and physiological reasons our moods tend to change with the season, Roecklein said. But a big factor in those seasonal mood swings is light.
“The scientific evidence says that length of day, which is shorter in the winter and longest in the summer, is the main seasonal variable that affects mood,” she said.
And since those sunsets are well on their way to getting earlier and earlier as soon as fall begins, it’s not unusual if you start to feel those mood shifts around the same time.
Your body knows when the sun is hiding
It’s your body’s circadian clock that monitors changes in day length, Roecklein explained. The circadian clock is the body’s internal time-keeper; it tells us when to feel sleepy and when to wake up, and plays a big role in a lot of other systems in our body, like hormone release, temperature regulation, metabolism and mood.
So when there’s less light during the day, some of those processes affected by the circadian clock, including ones that influence our mood, get disrupted. One study showed that individuals actually produce less serotonin ― one of the hormones that helps regulate mood and contributes to our feelings of wellbeing and happiness ― in the winter months, and more when there was more sunlight.
Other research shows changing light-dark cycles affect body temperature, how long it takes us to fall asleep, and how much we produce of melatonin, the hormone that triggers sleep. It also affects the production of stress hormones.
One key point to remember about the so-called “winter blues,” Roecklein said, is that “it’s a biological response to changing light levels ― NOT something we can overcome with sheer willpower alone.”
These cold weather pick-me-ups really work
If your symptoms aren’t that severe, your fall and winter don’t need to be downers. Here are a few things you can do.
1. Let the sunshine in.
Light ― or more specifically, the lack of it ― is part of what contributes to your low mood in the first place, Roecklin said. So doing things like opening the blinds and taking a walk outside in the sun in the morning can definitely lift your spirits.
2. Get moving.
Exercise (even just one workout) has been shown to be a big mood enhancer and stress buster. There are decades of research in people with depression that confirms a little sweat is a good idea, Roecklein said.
3. Eat right.
It’s raining. It’s cold. And you haven’t even dug that heavy sweater out of the back of your closet yet. While a batch of warm brownies may sound comforting, simple carbs and sugars can spike your blood sugar levels in your brain and then send them crashing down, with your mood tagging along for the ride.
Instead, focusing on fruits, vegetables, omega-3-rich foods, proteins and complex carbohydrates ― and drinking plenty of water ― can help keep energy and mood consistently up.
4. Make time for your friends.
There’s a reason a good chat with your bestie makes your day. Research shows spending time with your friends helps relieve stress, make you feel a sense of belong and improve well-being.
Spending time being social and engaging in hobbies and other activities you enjoy is a proven method to lift your mood, Roecklein said. It’s recommended for people battling depression.
How to tell when it’s more than a mood shift
All of us are susceptible to the mood-changing effects of seasonal shifts, but estimates suggest that about four to six percent of people have symptoms severe enough to warrant a clinical diagnosis of depression ― seasonal affective disorder, or SAD.
“It’s is a well-defined clinical diagnosis that’s related to the shortening of daylight hours,” Matthew Rudorfer a research psychiatrist and psychopharmacologist at the National Institute of Mental Health, said in an agency blog post. “It interferes with daily functioning over a significant period of time.”
And the condition should be diagnosed and treated. Three treatments have been proven to be effective for treating SAD: bright light therapy, cognitive behavioral therapy and antidepressant medications.
A psychologist can help determine if symptoms require treatment, but signs that you’re experiencing more than the typical “winter blues” are the same as the common symptoms of major depression: if you are not able to keep up with work, family and your regular behaviors or if you think treatment would help.
Sarah DiGiulio is The Huffington Post’s sleep reporter. You can contact her at sarah.digiulio@huffingtonpost.com.