The National Institute of Mental Health describes seasonal affective disorder as a type of depression with a recurrent seasonal pattern, with symptoms that usually last about 4 to 5 months a year. Most cases are winter-pattern, which means the time to notice early signs is now, as days shorten, not in January.
This guide to seasonal affective disorder symptoms follows NIMH’s publication (NIH Publication No. 23-MH-8138, revised in 2023). It explains the early signs, the winter-pattern symptoms, who is at risk and what treatments exist. This is general information, not a diagnosis. If you have thoughts of suicide, call or text 988 in the US, or contact your local emergency or crisis services.
What Seasonal Affective Disorder Is
NIMH defines SAD as a type of depression characterised by a recurrent seasonal pattern. Most cases are winter-pattern, and summer-pattern SAD is less common. The symptoms usually last about four to five months a year.
That makes it different from a brief dip in mood. The pattern repeats each year and affects daily life.
Early Signs to Watch For
NIMH lists general depression symptoms that can appear in SAD, and adds winter-pattern symptoms. Early signs often show up as a change from your usual self.
| Type | Signs (NIMH) |
|---|---|
| Mood | Feeling sad, anxious or empty for at least two weeks; hopelessness; irritability; guilt or worthlessness |
| Interest and energy | Loss of interest in activities; low energy; trouble concentrating |
| Body | Changes in sleep, appetite or weight; unexplained aches or digestive problems |
| Winter-pattern | Oversleeping; overeating with carbohydrate cravings and weight gain; social withdrawal, sometimes called hibernating |
| Most serious | Thoughts of death or suicide |
If you notice a combination of these signs repeating each autumn, write down dates and symptoms to share with a professional.
Who Is More at Risk
NIMH says SAD is far more common in women than men, and most cases begin in young adulthood. Risk is higher in northern regions with shorter winter days, such as Alaska and New England. It is also more common in people with depression or bipolar II disorder, and it sometimes runs in families.
| Risk factor | NIMH detail |
|---|---|
| Sex | More common in women |
| Age | Most cases begin in young adulthood |
| Location | Higher in northern regions with short winter days |
| Health history | Depression or bipolar II disorder |
| Family | Sometimes runs in families |
Treatments That Exist
NIMH lists four options, used alone or together. Only a professional can advise which suits you.
| Treatment | Notes (NIMH) |
|---|---|
| Light therapy | Daily session with a bright light box for winter-pattern SAD |
| Psychotherapy | Including CBT adapted for SAD |
| Antidepressant medication | Includes extended-release bupropion, FDA-approved to help prevent seasonal episodes |
| Vitamin D | Study results are mixed |
Healthy habits help alongside treatment. Our guides on sleeping better tonight and building a fitness habit that sticks may support routine.
When to Get Help
NIMH says to talk to a health care provider or mental health specialist if you notice symptoms. A questionnaire may be used to check whether you meet the diagnostic criteria. If you have thoughts of suicide, call or text 988 in the US or chat at 988lifeline.org, and call emergency services in an emergency. Outside the US, contact your local crisis service.
For wider context on stress, see our guide to the signs of chronic stress, and consider mental health days when you need them.
