Seasonal Affective Disorder (SAD)

Learn all about Seasonal Affective Disorder (SAD) and seasonal changes in mood. 

Last updated 30 October 2020

What is Seasonal Affective Disorder (SAD)?  

Seasonal affective disorder (SAD) is a type of depression that comes and goes in a seasonal pattern.

SAD makes you feel unhappy, anxious, tired, and irritable. It leaves you disinclined to socialise, and it undermines your ability to concentrate — all symptoms typical of depression.  

Do seasons affect everyone’s mood?  

There can be seasonal variations in everyone’s mental health. We know that things that are known to be good for our mental health such as exercising and spending time in green and blue spaces are harder to do when the days are short and nights are long. December is also a time when some of us may tend to eat and drink too much, run up debts, and then sometimes feel bad about these afterwards. 

Some people might experience Seasonal affective disorder (SAD) with symptoms of depression that come and go in a seasonal pattern (and are usually more intense in the lower light months). SAD appears to result from changes in the length of day, although more than lost sunlight may be involved. 

How can sunlight affect our moods?  

Our bodies’ rhythms cycle in 24-hour intervals — including sleeping and waking, the release of certain hormones, and the highs and lows of body temperature. This rhythm is essentially under the control of our genes, but it can adjust to environmental cues, notably changes in the light/dark cycle.  

Our brain's master clock uses these environmental cues of light and darkness to better align our internal rhythm to that of the world around us. Light and dark cues can cause bodily changes, which can in turn affect our hormones and impact our sleeping and eating habits, and our mood. 

Read more about this in our sleep report

What can we do to protect our mental health in darker months? 

If you have been feeling depressed, it is important to speak with your GP or care provider for more detail and to discuss which treatment may be most appropriate for you. 

There are also some steps you can take that may help alleviate some of the symptoms or even prevent seasonal changes in your mood:

  • Light, especially natural light, can have a huge effect on your overall mood. You should spend some time each day outside in the natural light as well as open your curtains to let as much of it in as possible. Avoid sitting in dark or dimly-lit rooms, and use lamps & mirrors to brighten up anywhere that is particularly dark.  
  • Exercise and spending time in green spaces are helpful for everyone’s mental health. Not only does regular exercise release chemicals such as endorphins, it can boost your self-esteem and help you concentrate, sleep and feel better. 

We may find that we are not alone; people are there to help and so many are facing similar challenges. Mental health matters on every day of the year. 

Protecting our mental health

Read more practical tips on things we all can do to protect our mental health:

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