Therapy for seasonal affective disorder (SAD): what works and how to choose

At the end of October the clocks go back and, overnight, it gets dark an hour earlier. For you, something inside switches off as well. You struggle to get out of bed even after nine hours' sleep, you are hungrier than usual and you cancel plans you would have accepted without a second thought in June. By March you are yourself again, and the following autumn it all starts over.

If this happens every year, it may be seasonal affective disorder, often shortened to SAD and sometimes called winter depression. It is not laziness or a slump you just have to sit out until spring: it is a type of depression, and it can be treated. If you are thinking about seeing a psychologist and looking for therapy for seasonal affective disorder, this guide explains when to seek help, which treatment works, what therapy involves, how long it takes, whether it works online and how to choose a professional.

When to see a psychologist for seasonal affective disorder

The NHS describes SAD as a type of depression that usually happens in the winter and goes away in the summer; some people have it the other way round, although this is less common. The symptoms it lists include:

• Low mood.
• A lack of interest in things you usually enjoy.
• Feeling guilty, hopeless or worthless.
• Feeling restless or irritable.
• Difficulty concentrating.
• Being more hungry and eating more than usual.
• Being more tired and sleeping more than usual.
• Thoughts of suicide or self-harm.

The NHS advises seeing a GP if you think you might have SAD, or if you have been diagnosed and treatment is not helping. It also explains that you may be diagnosed if you have had depression symptoms at a particular time of year for two years or longer. If you are having thoughts of harming yourself, do not wait for an appointment: call the 024 line in Spain (free, confidential, around the clock), 112, or your local emergency number.

Why it gets worse when the clocks go back

Nobody knows exactly what causes it. The NHS links it to reduced daylight in winter, which may affect brain chemicals such as melatonin and serotonin that are involved in mood and sleep patterns (the circadian rhythm). The change of clocks shows up too. A Danish study of 185,419 hospital contacts for depression between 1995 and 2012 found that after the switch from summer time to standard time, depressive episodes rose by 11% and took about ten weeks to return to their previous level. The spring change had no such effect. According to the study, this may be down to the distress of sunset suddenly coming earlier, marking the start of a long run of short days.

Seasonal affective disorder or just the winter blues?

The difference lies in how regular it is and how much it weighs on your life: depression symptoms that come back every year at the same time and take their toll at work, at home or with other people. To put numbers on it before you seek help, the Depression Test covers exactly what changes most in winter: one of its statements is "I have had trouble falling asleep or staying asleep, or I have slept too much", and another is "I have had a poor appetite or I have been overeating".

The NHS adds that some people have a period of feeling more energetic than usual at the start of spring or summer. If that energy feels excessive in your case, mention it to your psychologist: diagnostic manuals apply the seasonal pattern to both depression and bipolar disorder, and the treatment is different. The Bipolar Disorder Test can help you look into it.

Which treatment works for seasonal affective disorder

The NHS lists three treatments: antidepressants, talking therapies such as cognitive behavioural therapy (CBT) and light therapy. It also warns that many people need treatment every winter to stop symptoms coming back.

Psychological therapy has a large trial behind it that compared it directly with light. Rohan and colleagues randomly assigned 177 adults with SAD to six weeks of CBT tailored to the disorder or six weeks of light therapy. Both improved depression to the same degree, with almost identical remission rates: 47.6% and 47.2% on the clinical interview.

The difference came later. In the follow-up over the next two winters, there was no difference in the first year, but in the second winter 27.3% of those who had had therapy relapsed, compared with 45.6% of those who had used light, and their symptoms were milder. The study itself offers a practical explanation: light is a palliative treatment that works while you use it, and not everyone takes it up again each winter, whereas the gains from therapy proved more durable. We explain how depression is treated in general in Therapy for depression: when to see a psychologist, what works and how to choose.

What therapy for seasonal affective disorder involves

The version that was studied starts from classic cognitive therapy for depression and adapts it to winter. According to the trial's description, it moves through these stages:

1. Understanding what is happening. What SAD is, the role of light and why winter affects you the way it does.
2. Behavioural activation. Identifying and scheduling enjoyable activities to push back against winter apathy, instead of waiting for the motivation to return.
3. Questioning thoughts. As well as typical depressive thoughts, those tied to the season, such as the ones that come with darkness or bad weather.
4. A personal prevention plan. Learning to spot early the negative thoughts that anticipate winter and the behaviour changes that tend to come with it, as a signal to put what you have learnt into practice.

In the trial it was delivered in groups of four to eight people, with two 90-minute sessions a week, so that it finished before spring. We explain cognitive behavioural therapy in general in Cognitive behavioural therapy: what it is, how it works and what it treats.

What about light therapy and medication?

Light therapy involves sitting in front of a very bright lamp that simulates daylight. A meta-analysis by Pjrek and colleagues, covering 19 trials, found it more effective than placebo, although the studies were small and varied a lot. The NHS does not usually offer it because there is not enough evidence to tell whether it works, but it acknowledges that many people find it helps, and it advises speaking to a GP first: it may not be suitable if you have certain eye conditions or take medicines that make you more sensitive to light. If you buy a light box, it recommends one that is 10,000 lux, UV-free and carries a UKCA or CE mark. Antidepressants are always prescribed and monitored by a doctor. Psychological therapy can be combined with either option.

How long therapy for seasonal affective disorder takes

In Rohan's trial it was twelve sessions over six weeks, and the effect was still visible two winters later. In individual therapy, the pace and length are tailored to each person: if there is also anxiety, sleep problems or an underlying depression, it may take longer.

Does it help to start before winter?

It makes sense, but it has not been proven yet. A Cochrane review of psychological therapies to prevent SAD found only one trial, with 46 people who had mindfulness-based cognitive therapy in spring, and it showed no clear difference in relapses the following winter. The sensible approach is to seek help as soon as you notice the first symptoms and, if you already know winter hits you hard, to have a plan ready with your psychologist for when they start.

Does online therapy work for seasonal affective disorder?

The trials of therapy for SAD were carried out face to face, and we have not found any that compare the two formats for this condition. For CBT in general there is data: a meta-analysis by Carlbring and colleagues, covering 20 studies and 1,418 participants, found that therapist-guided internet CBT and face-to-face CBT produced equivalent results, although it notes that there are still few studies for each condition.

In winter it also has a practical advantage: you do not have to leave the house when it is already dark and moving is the last thing you feel like doing. That said, therapy will push you to get out into the daylight, not to stay in. If you have never had therapy by video call, Online psychologist: how to choose well and what to expect from video-call therapy may help.

How to choose a psychologist for seasonal affective disorder

These checks help you get it right:

• Registration as a health professional. This comes first.
• Experience in cognitive behavioural therapy and behavioural activation for depression.
• Someone who works on the pattern, beyond this winter. The prevention plan is part of the treatment.
• Someone who considers other possibilities, such as bipolar disorder, before assuming it is seasonal.
• Coordination with your doctor if you are considering antidepressants or light therapy.
• Flexibility: online sessions in the months when going out is harder.

A psychologist for seasonal affective disorder

At MyPsicoTest we recommend Xènia Capel Salcedo, a licensed clinical psychologist (COPC 14982) with a master's degree in Clinical Psychology and Psychotherapy. She sees clients in Igualada and Sant Sadurní d'Anoia and also through online therapy, and on her blog she has written an article about seasonal affective disorder. In it she explains that she works on it in a practical way in therapy: understanding your pattern so you can get ahead of it, gradually becoming active again when everything invites you to stop, reviewing the thoughts that come with low mood and building routines of light, sleep and movement for the dark months, coordinating with the doctor when needed. She works from an integrative, evidence-based approach: on her website she explains that she uses tools from cognitive behavioural therapy, EMDR, systemic therapy and person-centred therapy. Sessions are available in English, Spanish or Catalan, and the first contact is a free, no-commitment information consultation. She herself points out that in a serious crisis or psychiatric emergency, immediate in-person care is what is needed.

If your result worries you or you want a professional assessment, you can talk to Xènia Capel Salcedo, a licensed psychologist (COPC reg. 14982), who offers a free first consultation call and online therapy from anywhere.

MyPsicoTest team · Updated: 25 October 2026