Winter depression: what works, what does not and when to see a GP as the days close in

For Tom Allardyce, 38, a secondary school teacher in Inverness, winter used to begin in the second week of October and last until March. “I would notice I was sleeping 10 hours and still wanting more, eating like a bear, cancelling things,” he said. “By December I was a different person and by February I was not functioning. For years I thought it was just me being bad at winter.” It was seasonal affective disorder, diagnosed in 2021, and he now manages it with a light box, a running club and a GP who takes it seriously.

SAD is a form of depression tied to the seasons, and in the northern half of Britain, where in midwinter the sun is up for less than seven hours, it is common. Mental health charities estimate that around one in 20 adults in the UK has the condition in a clinical form and that a further one in five has milder symptoms, sometimes called the winter blues: lower energy, more sleep, carbohydrate cravings and a withdrawal from social life that lifts in spring. It is more common in women, in people in their 20s and 30s and, by a wide margin, the further north you go.

“The mechanism is reasonably well understood,” said Dr Fiona Ritchie, a consultant psychiatrist at a mental health service in Aberdeen. “Reduced daylight disrupts the body clock and lowers serotonin while raising melatonin. The result looks like depression with the dial turned towards sleep and appetite rather than insomnia and weight loss. The good news is that because the trigger is light, the treatments that work are fairly direct.”

The first is light therapy. A light box, which delivers 10,000 lux of white light at a distance of about 30cm, used for 20 to 30 minutes each morning from October to March, produces a meaningful improvement in about two-thirds of people with SAD within two weeks, according to the trials Ritchie cites. The boxes cost between £40 and £150 and the key is timing: morning, not evening, and consistently. A dawn-simulating alarm clock, which brightens gradually over 30 minutes before waking, helps a further group and is a reasonable first step for the milder version.

The second is daylight itself. Even a grey October morning in Aberdeen delivers 1,000 to 2,000 lux outdoors, 10 to 20 times what a lit office provides, and a 30-minute walk before 10am is the intervention Ritchie recommends to everyone, with or without a box. Allardyce’s running club, which meets at 7am three days a week on the Ness islands, is his version. “It is dark when we start and light when we finish,” he said. “That half an hour is the thing I would keep if I had to drop everything else.”

The third is talking therapy, specifically a form of cognitive behavioural therapy adapted for SAD, which the NHS offers in some areas and which trials suggest has longer-lasting effects than light alone. Antidepressants are an option for people whose symptoms are severe or who do not respond to light; the guidance is to consider them from October for people with a known pattern rather than waiting for the trough. Vitamin D, which almost everyone in Britain is short of in winter, is worth taking for general health but has not been shown to treat SAD on its own.

When to see a GP: Ritchie’s rule is that if winter symptoms have affected work, relationships or daily functioning for two or more years, it is a pattern that deserves a diagnosis, and the right time to go is now, in October, when a plan can be made before the worst of it. “People come in January and say they feel terrible,” she said. “They are right, and we can help, but by then they have lost three months. The time to start is the week the clocks change.”