Winter in Britain is not only cold. It is dark, and the darkness itself affects mood in ways that are measurable. The Royal College of Psychiatrists estimates that around 3 in every 100 people in the UK experience significant winter depression that meets the criteria for seasonal affective disorder (SAD), and more than a million people in the UK are estimated to live with SAD during the winter months. Far more feel the milder version: around one in five people experience the "winter blues" — low energy, low mood and a pull towards staying indoors that lifts when the light returns.
Loneliness sharpens the effect. An Office for National Statistics survey covering 3 December 2025 to 4 January 2026 found that 24% of adults in Great Britain reported feeling lonely often, always or some of the time. The figure was highest among adults aged 30 to 49, at 30%, followed by 16- to 29-year-olds at 27%.
What SAD is, and what it is not
Seasonal affective disorder is a type of depression that comes and goes with the seasons, usually starting in autumn, peaking in winter and lifting in spring. The NHS describes the usual symptoms as a persistent low mood, a loss of pleasure or interest in normal everyday activities, irritability, feelings of despair, guilt and worthlessness, feeling lethargic and sleepy during the day, sleeping for longer than normal, craving carbohydrates and gaining weight, and difficulty concentrating. It is more common in women than men — one study found women two to three times more likely to be diagnosed — and young people between 16 and 30 are more likely to be diagnosed than older adults.
The exact cause is not fully understood, but the leading explanation is reduced sunlight disrupting the body's internal clock, lowering serotonin and disturbing melatonin, the hormone that regulates sleep. That is why the treatments that work are the ones that address light, routine and connection, and why the NHS lists light therapy, talking therapies such as cognitive behavioural therapy (CBT) and antidepressants among the options.
Dr Hana Patel, an NHS doctor specialising in sleep and mental health, told the news agency SWNS in September 2026 that a light box can help, but only the right kind: "A light box or lamp that simulates sunlight should generally provide an exposure to 10,000 lux of light, and produce as little UV light as possible to be safe for your eyes." She added that there is evidence to support the lamps, but that everyone is different. Speak to a GP or pharmacist before trying light therapy: it may not be suitable with some eye conditions or medicines that increase light sensitivity.
Light, routine and movement — the evidence, not the slogans
Light matters most in the morning. Get outside within an hour or two of waking, even if it is grey and overcast — daylight on a cloudy day is still far brighter than indoor light. A twenty-minute walk in daylight does more than an hour sitting by a window. At home, open curtains fully, sit near a window when you work, and keep rooms bright during the day.
Routine is the second anchor, and it works because shapeless days make low mood worse. Bedtimes drift, mornings get later, meals become irregular, and each day starts to feel the same. A few anchors are enough: a regular wake time, a shower and getting dressed, one planned activity a day, and a roughly regular bedtime. On the hardest days, a routine of three small things — get up, get dressed, go outside — is a genuine achievement.
Movement helps, but winter is not the moment for punishing goals. A walk, a swim, a gentle jog, a home workout, a dance class, a kickabout in the park — whatever fits your life and your body. If getting outside feels too hard, start indoors with stretching or yoga. Going with someone else — a friend, a partner, a dog — makes it easier still, and it answers the loneliness figures at the same time.
Stay connected, deliberately
When mood drops, going out feels harder, and staying in can leave you feeling worse. Breaking that pattern does not require big social occasions — a phone call, a cup of tea with a neighbour, a walk with a friend, a message to someone you have been meaning to catch up with. If you work from home or live alone, connection needs to be deliberate. Join something regular: a class, a club, a volunteering shift, a walking group. Libraries, community centres and places of worship often run free or low-cost winter social sessions.
It also helps to tell someone how you are feeling. You do not need to make a big announcement. A simple "I have been feeling a bit flat lately" to a friend or family member is often enough to open a conversation, and most people respond with far more understanding than we expect.
Where to get help, and how long it takes
Your GP is a good first step. GPs hear about low mood every day, and there is nothing to be embarrassed about. They can talk through options, which may include talking therapies, lifestyle changes or medication. The main NHS route for anxiety and depression is NHS Talking Therapies, formerly known as IAPT. In 2024/25, 1.81 million people in England were referred to the service, 1.21 million entered treatment, and 670,400 finished a course of treatment. The average wait for a first treatment was 20.2 days.
The service has formal targets — 75% of people should start their first treatment within six weeks, and 95% within 18 weeks — and it is beating the first of those. In December 2025, 128,415 new referrals were received, and of those who finished a course of treatment that month, 88.6% had waited less than six weeks and 98.0% less than 18 weeks.
If you need to talk to someone right away, call Samaritans free on 116 123, any time, day or night. Samaritans volunteers responded to more than 3.3 million calls for help in 2025 — roughly one call every ten seconds — and over 20,000 people volunteered for the charity. Mind's infoline is 0300 123 3393. If you feel you might act on thoughts of harming yourself, call 999 or go to your nearest A&E. The darkness will lift in spring. The help does not have to wait until then.