Seasonal affective disorder (SAD)

Also called SAD or Winter depression

Seasonal affective disorder (SAD) is a type of depression that follows a seasonal pattern. Symptoms are usually more noticeable and more severe during the autumn and winter, when there is less daylight. It is thought to be linked to the effect of reduced sunlight on hormones such as melatonin and serotonin and on the body clock.

Last updated Nov 9, 2026

What it is

Getting as much natural light as possible, regular exercise and managing stress can help.

Treatments include talking therapies such as CBT, antidepressants, and light therapy using a special lamp.

Common signs

  • A persistent low mood
  • Loss of pleasure or interest in everyday activities
  • Feeling irritable
  • Feeling lethargic and sleepy during the day
  • Sleeping longer and finding it hard to get up
  • Craving carbohydrates and gaining weight

How it is usually diagnosed

  • Talking with a GP about mood, lifestyle, diet and sleep, and how they change with the seasons

Records worth keeping

Keeping these together makes each appointment easier, especially when you see a new doctor:

  • GP notes
  • Therapy plans
  • Medicine lists
  • A mood diary

Questions to ask your doctor

  • Would light therapy help me?
  • Should I start treatment before winter?
  • Which talking therapies are available?

When to get help right away

Call 112 or go to the nearest emergency department if you have:

  • Thoughts of harming yourself: get urgent help, call 112 if in danger

This page is general information. It is not a diagnosis and does not replace a doctor who knows your history. Medfold keeps your records organised; it does not interpret them.

Sources