This page is general information, not medical advice. If you think you may have seasonal affective disorder (SAD), speak to a doctor or other health professional.
SAD is depression that follows a seasonal pattern. The NHS says the main symptom is depression that returns in winter and lifts in summer. A summer pattern also exists but is less common. The US National Institute of Mental Health (NIMH) says episodes typically last about 4 to 5 months a year.
Symptoms
The NHS lists low mood, loss of interest in usual activities, feelings of guilt or hopelessness, restlessness or irritability, difficulty concentrating, increased appetite and increased tiredness or sleep. Thoughts of suicide or self-harm are also listed; if you have them, see where to get urgent help below.
Related Reading
NIMH describes the winter pattern as often including oversleeping, overeating with carbohydrate cravings, and social withdrawal. For the summer pattern it lists insomnia, poor appetite, restlessness, agitation, anxiety and, in some cases, violent or aggressive behaviour.
Who is more at risk
NIMH says SAD is much more common in women than in men and in people living farther north, and that it usually begins in young adulthood. It is also more common in people with depression, bipolar II disorder or certain other mental disorders, and it sometimes runs in families.
Treatment
- Talking therapies: the NHS lists cognitive behavioural therapy (CBT). NIMH describes a CBT version for SAD, typically two group sessions a week for 6 weeks, and says it is about as effective as light therapy with benefits that may last longer.
- Antidepressants: listed by both. NIMH says they usually take 4 to 8 weeks to work.
- Light therapy: NIMH describes daily use of a 10,000-lux light box for about 30 to 45 minutes, usually in the morning, mainly for winter-pattern SAD. The NHS says it is not usually available on the NHS because there is not enough evidence to tell whether it works, though many people find it helps. It says to speak to a GP first, as it may not suit people with some eye conditions or on medicines that increase light sensitivity.
- Vitamin D: NIMH says the evidence is mixed, with some studies finding it as effective as light therapy and others finding no effect. It can interact with some medications, so talk to a clinician first. Our vitamin D post covers daily amounts.
The NHS notes that many people need treatment each winter to stop symptoms returning.
When to get help
The NHS says to see a GP if you think you might have SAD, or if you have been diagnosed and treatment is not helping. People aged 18 or over, or 16 or over in some areas, can refer themselves to NHS talking therapies without seeing a GP.
Where to get urgent help
United Kingdom (NHS):
- Life at immediate risk, or you cannot keep yourself or someone else safe: call 999 or go to A&E.
- Urgent but not an immediate danger: use 111.nhs.uk or call 111 and choose the mental health option. You can also ask for an urgent GP appointment.
- Someone to talk to: Samaritans, 116 123, free and confidential. Under 19: Childline, 0800 1111.
United States (NIMH):
- Crisis or thoughts of suicide: call or text 988 (Suicide and Crisis Lifeline), or chat at 988lifeline.org.
- Life-threatening situation: call 911.
Elsewhere, contact your local emergency number or health service.
