How Does Seasonal Affective Disorder (SAD) Affect Your Sleep?

Learn how SAD affects your mind, body, and sleep and what you can do about it.

By Andrea Pisani Babich

Many people experience the occasional winter blues when the hours of daylight decrease, the weather turns colder, and the nights go on forever. But a small percentage of people experience a type of major depression that lasts an entire trigger season (fall/winter or spring/summer), which apparently resolves on its own when the season changes only to return when the trigger season returns once again.

These people suffer from what’s known as Seasonal Affective Disorder, or SAD, and while it has often been dismissed as a mild, temporary condition, its symptoms can be devastating, especially on your sleep patterns.

What Is Seasonal Affective Disorder?

Seasonal Affective Disorder, or SAD, is a recurring major depressive episode that affects the energy level, appetite, and sleeping patterns of people who suffer from it.

Winter-onset SAD occurs in the fall and lasts through the winter. Like some other forms of depression, winter-onset SAD is characterized by fatigue and sluggishness, sleeping more than usual, and difficulty concentrating. Although there are treatments for the disorder, symptoms spontaneously go into remission with the arrival of spring and summer.

Less common than the winter version, summer-onset SAD begins when the weather turns warm and the days get longer. It features the opposite symptoms. People with summer-onset SAD feel restless, experience insomnia, and lose their appetites. Their symptoms go away with the arrival of fall, and they remain symptom-free until winter yields to spring and summer-like conditions return.

What Are the Symptoms of Seasonal Affective Disorder?

The symptoms of SAD depend on which season triggers the disorder.

Symptoms of Fall/Winter SAD include:

  • Fatigue and lethargy in spite of sleeping more than normal
  • Disordered mood including sadness, irritability, and frequent crying
  • Lack of energy and decrease in activity levels
  • Social withdrawal leading to feelings of isolation that exacerbate depression
  • Carbohydrate and sugar cravings that tend to lead to weight gain

Symptoms of Spring/Summer SAD include:

  • Insomnia
  • Disordered mood including irritability and anxiety
  • Loss of appetite that may lead to weight loss
  • Agitation and restlessness
  • Violent behavior in some cases

Even though the symptoms of SAD are only present for a relatively short duration, they can be severe and include thoughts of suicide. SAD is treatable and should not be ignored, especially if symptoms include suicidal thoughts. A primary care physician should be consulted right away if the depression leads to suicidal thoughts.

If you or someone you know experiences thoughts of suicide, call the National Suicide Prevention Lifeline 24/7 at 1-800-273-8255.

What Are the Causes of SAD?

Seasonal Affective Disorder gets its name from the change of seasons that triggers its onset. The seasonal decrease or increase in hours of sunlight and its effect on your physiology is the most important external factor causing SAD. The exact internal causes of SAD are still controversial, but experts agree they involve three main factors.

Serotonin regulation

Serotonin is a brain chemical that influences your mood and contributes to your well-being and happiness. People susceptible to SAD appear to be unable to maintain healthy levels of serotonin in the waning hours of sunlight of fall and winter. This diminished serotonin activity leads to depression.  

Melatonin production

Melatonin is a hormone that causes drowsiness in response to darkness. The additional hours of darkness in winter along with the less direct angle of the sun’s rays increases the production of melatonin in people who suffer from SAD, making them sleepy and lethargic. In the summer, the increased hours of sunlight delays the production of melatonin, making it harder for people with summer-onset SAD to relax into a peaceful sleep at night.

Related: Can you overdose on melatonin?

Circadian rhythms

Circadian rhythms affect your body, mind, and behavior on a daily cycle. Hunger and digestion, body temperature fluctuations, and your sleep/wake cycle are just some of the many functions governed by your circadian rhythms, which are in turn affected by serotonin and melatonin levels.

Related: Can you change your circadian rhythm?

When seasonal shifts in sunlight duration disrupt the normal levels of serotonin and melatonin, the circadian rhythms of people with SAD are unable to make the seasonal adjustment necessary to maintain healthy mind and body functions. Often the most noticeable symptom of SAD is disordered sleep.

Who Is Most at Risk for Seasonal Affective Disorder?

SAD affects anywhere from 1 to 9 percent of people in the Western Hemisphere where it has been studied. If you live far north of the equator, you are more likely to experience SAD than people who live in southern latitudes and four times more women than men experience SAD. Cold-weather SAD is much more common than summertime SAD, affecting about 10% of people who experience SAD.

Factors that may increase your risk of experiencing Seasonal Affective Disorder include:

  • Family history. If you have blood relatives who have suffered from SAD or another form of depression, your risk of being affected by SAD is increased.
  • Prior major depression or bipolar disorder. Symptoms of these mood disorders may worsen when summer turns to fall or winter yields to spring.
  • Doing rotational shift work. There may be a higher incidence of SAD among workers whose shifts rotate around the clock because of their continually changing exposure to daylight.

SAD and Sleep Troubles

Seasonal Affective Disorder can affect your sleep habits no matter what time of year it strikes. If you experience winter SAD, you may feel like you are sleeping all the time, and when you aren’t sleeping, you’re wishing you were. The overwhelming feeling of lethargy and lack of interest in otherwise enjoyable activities doesn’t seem to go away no matter how much you sleep.

Summer SAD can make it hard for you to sleep because your internal clock is slow to tell your body and mind to power down. The agitation and anxiety you may feel in addition to the heat and humidity of the season can make sleeping impossible for with summer-onset SAD.

What can you do to sleep better while you’re struggling with SAD?

How to Sleep Better with SAD

There are steps you can take to sleep better and help prevent the change in the season from creating a dramatic change in your sleep pattern.

Light therapy

Since the physiological changes that appear to cause SAD are triggered by changes in sunlight exposure, light therapy, or phototherapy, is often the first choice of treatment options for people with fall/winter SAD. It involves exposure to very bright light from a special light box for the first hour of waking each day.

Meant to mimic sunlight, the light box helps to regulate your disordered serotonin and melatonin levels, letting your body know when it is time to be alert and when it is time to power down so you can sleep. Be sure to consult with your doctor about what kind of light box is safe for you, as well as how and when to use.


A type of psychotherapy known as cognitive behavioral therapy can help you learn ways to cope with your SAD symptoms by resisting the urge toward isolation and inactivity. This form of talk therapy can identify negative thoughts and behaviors that may contribute to your SAD symptoms and help you manage stress.


Your doctor may prescribe an antidepressant, especially if your symptoms of SAD are severe. If SAD is an annual disruption in your life, your doctor may recommend that you take the antidepressant before the trigger season and after it is over. Be aware the antidepressants often take several weeks to take full effect and not every antidepressant works for everyone. You may need to do some trial and error over several weeks to find the right treatment for you.

Home remedies

There are several things you can do without the advice of a doctor that will help you manage your stress, keep your body moving, and let you get the rest you need. They include simple activities like

  • Meditation
  • Yoga
  • Walking outdoors, especially in sunshine
  • Physical exercise
  • Incorporate CBD oil into your nightly routine, especially for summer SAD
  • For winter SAD, get as much exposure to morning sunlight as possible in the winter. If you have insomnia in the summer, darken your rooms on summer evenings to help stimulate melatonin production.
  • Clean up your sleep hygiene by keeping your bedroom around 67 degrees, turning off your electronic devices at least an hour before bedtime, and keeping consistent sleep/wake times.

If you’re affected by SAD, one of these treatment options may be able to help you.

Sacrificing your sleep should never be an option, especially when your mental health is in serious danger of being affected. Be proactive about taking care of your sleep health and follow these tips to help you combat SAD and stay well rested every season of the year.

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