Seasonal Affective Disorder – SAD


Seasonal affective disorder (SAD) is a type of depression that comes and goes in a seasonal pattern. It is sometimes known as “winter depression” because the symptoms are more apparent and tend to be more severe during the winter.

The symptoms often begin in the autumn as the days start getting shorter. They’re typically most severe during December, January and February.


Symptoms include:

  • a persistent low mood
  • a loss of pleasure or interest in normal everyday activities
  • feeling irritable
  • feelings of despair, guilt and worthlessness
  • feeling lethargic (lacking in energy) and sleepy during the day
  • sleeping for longer than normal and finding it hard to get up in the morning
  • craving carbohydrates and gaining weight We may all suffer from some of these symptoms in the winter – e.g. comfort eating; reluctant to socialise so much and feeling fed up but for some people these symptoms can be severe and have a significant impact on their day-to-day activities.


What causes SAD?

The effects of light

When light hits the back of the eye, messages are passed to the part of the brain that controls sleep, appetite, sex drive, temperature, mood and activity. If there’s not enough light, these functions are likely to slow down and gradually stop.

Some people seem to need a lot more light than others for their body to function normally. They are therefore more likely to develop SAD symptoms if there are low levels of light.

Low serotonin levels

The brain uses the chemical serotonin to regulate our mood.

People experiencing depression have been found to have lower levels of serotonin, particularly in winter. It is thought there may be particularly strong seasonal variations in how this process works in people with SAD.

High melotonin levels

When it’s dark, the brain produces the hormone melatonin which makes us sleep. When it becomes light again, it stops producing melatonin and we wake up.

It has been found that people with SAD produce much higher levels of melatonin in winter than other people. (This is also what happens to animals when they hibernate).


Consult your GP if your depression is severe.

However, there are some things that you can do to try and help yourself:

  • try to get as much natural sunlight as possible – even a brief lunchtime walk can be beneficial
  • make your work and home environments as light and airy as possible
  • sit near windows when you’re indoors
  • take plenty of regular exercise, particularly outdoors and in daylight
  • eat a healthy, balanced diet
  • if possible, avoid stressful situations and take steps to manage stress

It can also be helpful to talk to your family and friends about SAD, so they understand how your mood changes during the winter. This can help them to support you more effectively.

Cognitive behavioural therapy (CBT) is based on the idea that the way we think and behave affects the way we feel. Changing the way you think about situations and what you do about them can help you feel better.

Counselling is another type of talking therapy that involves talking to a trained counsellor about your worries and problems.

The aim of the sessions is to find out whether anything in your past is affecting how you feel today.

Light Therapy – Some people with SAD find that light therapy can help improve their mood considerably. This involves sitting by a special lamp called a light box, usually for around 30 minutes to an hour each morning.

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Light boxes come in a variety of designs, including desk lamps and wall-mounted fixtures.  They produce a very bright light.

Dawn-stimulating alarm clocks, which gradually light up your bedroom as you wake up, may also be useful for some people.

The light produced by the light box simulates the sunlight that’s missing during the darker winder months.

It’s thought the light may improve SAD by encouraging your brain to reduce the production of melatonin (a hormone that makes you sleepy) and increase the production of serotonin (a hormone that affects your mood).

Speak to your GP if you’re unsure about the suitability of a particular product.

Does light therapy work?

There’s mixed evidence regarding the overall effectiveness of light therapy, but some studies have concluded it is effective, particularly if used first thing in the morning.

It’s thought that light therapy is best for producing short-term results.



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