The symptoms of depression include tiredness, low motivation, loss of enjoyment, loss of concentration and memory, thinking negatively and feeling hopeless about the future. Depression can range from being mild, to being severe and accompanied by suicidal thoughts or urges. Depression can be triggered by a difficult life event, such as problems at work, bereavement or a relationship break down, but sometimes depression has no obvious trigger but may have accumulated over time.

CBT has been proven to help with depression. Studies have found that when someone is taking no medication CBT will help them, but it will also help people on medication to make more progress. When someone is depressed their daily routine is often characterised by under activity, over activity and/or few pleasurable activities. CBT addresses activity levels, and teaches people to challenge their negative thoughts about themselves, their situation, and their future. Even if the situation that triggered the depression cannot be changed, making these changes will help someone adjust to their circumstances better and their mood increase.