As the clocks prepare to go back and the evenings draw in, it’s worth being specific about something that gets talked about a lot but explained properly less often: seasonal affective disorder, or SAD. It isn’t the same thing as generally finding winter a bit gloomy — it’s a recognised, recurring type of depression with a genuine seasonal pattern, and it’s worth understanding on its own terms rather than as a vague catch-all for “the winter blues.”
What SAD actually is
SAD is a type of depression that follows a seasonal pattern, with episodes typically starting in autumn, becoming most pronounced through December, January and February, and lifting again in spring or summer. A small number of people experience the reverse pattern, with low mood in summer instead. What distinguishes it from general low mood is the pattern — a recurring, seasonal episode that shows up and resolves at roughly the same time each year, rather than a single difficult stretch.
What’s thought to cause it
The exact cause isn’t fully understood, but SAD is thought to be linked to reduced exposure to daylight during the shorter autumn and winter days. Reduced daylight is believed to affect brain chemicals involved in mood and sleep, including melatonin and serotonin, which is part of why the self-care approaches below focus so heavily on daylight exposure rather than being a random list of general wellness tips.
Recognising the symptoms
SAD shares many features with depression more broadly, alongside some seasonal-specific patterns. Common symptoms include:
- A persistent low mood, or loss of interest in things you’d normally enjoy
- Feelings of guilt, hopelessness, or low self-worth
- Irritability and difficulty concentrating
- Being hungrier than usual and eating more, particularly carbohydrates
- Feeling unusually tired and sleeping more than normal
- In more severe cases, thoughts of self-harm or suicide
That last point matters enough to say plainly: if you’re having thoughts of self-harm or suicide, that’s not something to wait out until spring — it’s worth contacting a GP or a crisis service without delay.
What the NHS says actually helps
A few self-care approaches are consistently recommended, and they’re worth taking seriously precisely because they target the daylight mechanism SAD is linked to, rather than being generic advice:
Get outside in daylight, every day. Even a short walk at lunchtime, in genuine daylight rather than through a window, is a meaningful part of managing symptoms — not just a nice-to-have.
Keep your usual routine and social contact going. It’s a common instinct to withdraw when mood drops, but maintaining regular activities and staying in contact with other people is part of the recommended approach, not incidental to it.
Stay physically active. Regular exercise is linked to improved mood generally, and that link holds for SAD specifically.
Protect your sleep routine. Keeping consistent sleep and wake times, and avoiding screens late in the evening, supports the same body clock that reduced daylight disrupts. Sleep is one of the areas with genuinely strong evidence behind it as a foundation for everyday mood and health more broadly, which makes it worth prioritising rather than the first thing to sacrifice when a difficult winter stretch hits.
When self-help isn’t enough
For some people, self-care measures alone aren’t sufficient, and that’s not a sign of doing it wrong — it’s a sign the condition needs a different level of support. Recognised treatment options include light therapy (using a specifically designed SAD lamp, typically 10,000 lux and UV-free, rather than an ordinary desk lamp), cognitive behavioural therapy (CBT), and, where appropriate, antidepressant medication. Many people need some form of treatment each winter rather than a one-off fix, which is worth knowing so it doesn’t feel like a setback if symptoms return the following year.
When it’s worth speaking to a GP
It’s worth talking to a GP if low mood is affecting your daily life, work, or relationships, if it’s following a clear seasonal pattern year after year, or if self-care measures alone aren’t making a meaningful difference. A GP can properly assess whether what you’re experiencing is SAD specifically, rule out other causes, and talk through which treatment options — light therapy, talking therapy, medication, or a combination — might suit your situation. None of the guidance above is a substitute for that individual assessment, particularly if symptoms are severe or include thoughts of self-harm.
The practical takeaway
SAD is a real, recognised condition with a genuine seasonal pattern, not just a way of describing normal winter gloominess — and the evidence-backed response to it is more specific than generic “self-care” advice, centring on daylight exposure, routine, and activity, with proper clinical treatment available when that’s not enough. Treating a recurring winter low mood as worth investigating, rather than something to just get through, is worth taking seriously on the evidence alone.
Sources: NHS — Seasonal affective disorder (SAD), NHS inform Scotland — Seasonal affective disorder, South London and Maudsley NHS Foundation Trust — Seasonal affective disorder
