Is it the Winter Blahs or Seasonal Affective Disorder (SAD)?

February 26, 2026

Girl sits on the window sill of the window and looks at the falling snow. The concept of home comfort, season, solitude

With the bright lights and joyful celebrations of the holiday season behind us, it’s normal to experience a drop in mood—also known as the winter blahs. Baby, it’s cold outside, so most of us spend less time outdoors during the winter months. That alone can make us feel sadder than usual.

But feeling a bit sad isn’t the same thing as SAD, short for seasonal affective disorder.

SAD is a type of depression that often occurs during the late fall and throughout the winter months. The disorder goes beyond the usual blahs. Women and residents of northeastern states are at higher risk of developing symptoms than those living in other parts of the country.

What causes SAD?

A chain reaction, starting with inadequate exposure to sunlight, can lead some people to develop SAD, year after year.

As sunlight helps the body process vitamin D, a lack of sunlight can cause vitamin D deficiency. That vital nutrient promotes the activity of serotonin—a brain chemical that helps to regulate mood. According to the National Institute of Mental Health (NIMH), people with SAD exhibit lower-than-normal serotonin levels during the winter months.

Less serotonin results in more melatonin, the “sleep hormone.” That’s the next link in the chain. Too much melatonin may be partly responsible for the changes in mood, sleep, energy and behavior that SAD sufferers experience.

What are the symptoms of SAD?

depressed mood
negative thinking
difficulty concentrating
reduced desire to socialize
fatigue
changes in sleep patterns
increased carbohydrate cravings

What steps can I take to relieve these symptoms?

If you’re experiencing any of the symptoms listed above, consider the following action steps per Dr. Allen-Dicker, Assistant Attending Psychologist and Assistant Professor of Psychology at Weill Cornell Medicine:

Get outside and exercise during the day for an hour.
Work on developing a healthier sleep schedule. Try not to sleep too much or too little. Aim for 7 to 9 hours a night.
Be more socially active.
Challenge those negative thoughts…
…and above all, take care of yourself.

Prioritize your mental health

Additionally, Dr. Allen-Dicker suggests specific steps that can lift your mood and your overall functioning. These are relevant all year long, but they’re especially important during the late fall and winter:

Aim for 7 to 9 hours of sleep per night.
Open your curtains first thing in the morning.
Set a regular bedtime, and wake up at the same time each day.
Challenge negative thoughts by connecting with friends and keeping a gratitude journal.
Instead of wolfing down more candy and cookies, enjoy complex carbs such as whole grain bread, pasta and rice, or healthy simple ones, like those found in fruit.
…and above all, take care of yourself.

Treatments for SAD

There are three proven treatments for SAD: cognitive behavioral therapy (CBT), antidepressant medication and light therapy.

A mental health professional at Weill Cornell Medicine can provide the first two. But you can literally purchase the third—light therapy—in the form of a light box. Sit in front of it each morning for 30 to 45 minutes, and you may be surprised by its mood-lifting effects. “A light box can be a great investment,” Dr. Allen-Dicker says. “My patients swear by it!”

Some people also benefit from taking a vitamin D3 supplement. While no substitute for sunlight, it can boost your vitamin D levels at a time of year when sunlight is in short supply.

Be aware that there’s no need to accept SAD as a “natural” companion throughout the winter months. There’s a lot you can do to counter it.

If you suffer from SAD or any other type of depression,  find a therapist at Weill Cornell Medicine.