Seasonal affective disorder (SAD) is a type of depression that comes and goes with the seasons, usually starting in autumn and lifting in spring. It’s more common the further you live from the equator, and many people who move from tropical countries to places like the UK, Ireland, Canada or Northern Europe notice it in their first winters. Symptoms include low mood, low energy, oversleeping and craving carbohydrates. Light therapy, talking therapy and antidepressants can all help.
Symptoms
- Persistent low mood most days
- Loss of interest in usual activities
- Low energy and feeling sluggish
- Sleeping much more than usual, difficulty waking
- Craving carbohydrates and weight gain
- Difficulty concentrating
- Irritability, withdrawing from people
- Feelings of hopelessness or worthlessness
Why it happens
Shorter days and less sunlight are thought to disrupt the body clock and affect brain chemicals such as serotonin and melatonin. Night-shift work, which reduces daylight exposure further, can add to the risk.
Treatment
- Light therapy: sitting near a special light box (often 10,000 lux) for about 30 minutes each morning. Choose a medically designed box and ask a doctor first if you have eye conditions or bipolar disorder.
- Talking therapy: CBT can help, including CBT adapted for SAD.
- Antidepressants: such as SSRIs, sometimes started before winter for people with a clear pattern.
10 ways to cope
- Get outside in daylight every day, especially in the morning
- Sit near windows at home and work
- Exercise regularly, ideally outdoors
- Keep a regular sleep and wake time
- Plan enjoyable activities in winter months
- Eat balanced meals and limit alcohol
- Stay connected with friends and family, including video calls home
- Consider vitamin D supplements in winter if advised in your country
- For night workers: get bright light during waking hours and protect daytime sleep
- Talk to your GP early if you notice the pattern returning
When to get help urgently
If you have thoughts of harming yourself or ending your life, contact emergency services, a crisis line or your doctor immediately.
Frequently asked questions
Is winter blues the same as SAD?
“Winter blues” is milder. SAD is a form of depression that significantly affects daily life.
Can people in sunny countries get SAD?
It’s less common near the equator but can happen, including in reverse (summer pattern).
Related reading: Loneliness abroad · Self-care for nurses
Checked against NHS guidance on SAD. Updated 5 November 2026. This is a sensitive topic; if you’re struggling, please reach out to a health professional or someone you trust.