Winter blues vs seasonal depression: how to tell the difference

The winter blues are not a diagnosis. They are a feeling most people recognize: it is dark at 5 p.m., your energy drops, leaving the house takes more effort and everything looks a little grayer. According to the US National Institute of Mental Health (NIMH), many people feel “down” or have the “winter blues” as the days get shorter.

This kind of dip tends to change from day to day. Good news, a sunny weekend or dinner with a friend can lift it. You still go to work, see people and do the things you like; they just take more effort than in July.

The UK's National Health Service (NHS) describes seasonal affective disorder as “a type of depression that usually happens in the winter”. According to NIMH, most cases begin in late fall or early winter and ease in spring and summer, with symptoms lasting about four to five months of the year. A less common summer pattern also exists.

NIMH also notes that SAD is much more common in women than in men, more common in people who live far from the equator, where winter days are shorter, and that it usually starts in young adulthood.

The condition was first described in a 1984 paper in the Archives of General Psychiatry. The researchers wrote about 29 patients whose depressions came and went with the seasons; oversleeping, a bigger appetite and cravings for carbohydrates stood out.

According to the NHS, the main symptom is depression that appears in winter and lifts in summer. The symptoms it lists:

• a persistent low mood
• losing interest in things you normally enjoy
• feeling guilty, hopeless or worthless
• feeling restless or irritable
• finding it hard to concentrate
• feeling hungrier and eating more than usual
• feeling more tired and sleeping more
• thoughts of suicide or self-harm

This list is not a test. Recognizing a few items does not mean much on its own; the real questions are how long it lasts and how much it gets in the way of your life. If the last item applies to you, go straight to the support section at the end of this guide.

Three questions help. Does it stop you from doing your work, keeping up with people or looking after yourself? Has it lasted longer than two weeks? The NHS advises seeing a doctor if you have symptoms of depression for most of the day, every day, for more than two weeks. And did something similar happen last winter? The NHS says SAD may be diagnosed if symptoms appear at the same time of year for two years or more.

Nobody knows the exact cause. The NHS says SAD is thought to be linked to the reduced daylight in winter: less light may affect brain chemicals such as melatonin and serotonin and the body's sleep and wake (circadian) rhythm.

The clock change itself does not take daylight away. According to the US National Institute of Standards and Technology (NIST), switching back to standard time moves one hour of daylight from the evening to the morning. That is why, in the US and Europe, the evenings seem to go dark overnight in late October and early November, while the days themselves keep shortening slowly until late December.

The self-help steps the NHS lists for SAD work for the milder winter blues too:

• Get as much natural daylight as you can, ideally outdoors every day. A short walk at lunchtime counts.
• Exercise regularly. It does not have to be intense.
• Stay in touch with people. Winter makes hiding easy, so put one small plan with a friend on the calendar.
• Keep up your usual activities, even when you do not feel like it.
• Go to bed and get up at the same times.
• Avoid drinking heavily, drugs and screens right before bed.

On light therapy lamps, the NHS is honest: they are usually not available on the NHS because the evidence is limited, although many people find them helpful. It advises talking to a doctor first, because a lamp may not suit people with some eye conditions or people taking medicines that make them more sensitive to light. If you buy one, it suggests a lamp with a brightness of 10,000 lux that filters out UV light.

If you are diagnosed with SAD, a doctor may suggest talking therapy such as cognitive behavioral therapy (CBT), antidepressants or light therapy. NIMH also lists vitamin D among the treatments studied. These are decisions to make with a doctor.

Memory is a poor witness here: in December, it is hard to recall how October actually felt. A simple daily log closes that gap.

1. 1Mark your mood at the same time every day. A five point scale is enough; you do not need to write much.
2. 2Add one or two pieces of context. How many hours you slept, or a one word tag such as “outside” or “dark early”.
3. 3Compare months. Do your October days look different from your December days? Did the dip start after the clocks changed?
4. 4Keep going into spring. A seasonal pattern shows itself when the mood lifts as the light comes back.

One winter of entries is not a pattern; doctors look at two years or more. But this year's log becomes next year's comparison. We explain the method in our guide on how to keep a mood journal.

In Pixmood you mark your day in about five seconds by tapping one of five moods: Great, Good, Calm, Low or Rough. In the free month mosaic you can see whether Low and Rough days, blue and purple in the default theme, pile up as the evenings darken. If you like, add a tag of up to 20 characters, such as “walk” or “dark early”.

Pixmood Pro shows all 365 days of the year on one screen, so a seasonal band stands out at a glance; our Year in Pixels guide explains how to read one. With Pro you can also log your sleep hours and see how sleep relates to your mood.

The limits: Pixmood cannot tell you whether you have SAD, and it is not a screening or diagnostic tool. It does not measure daylight or sleep by itself and does not connect to Apple Health; it only records what you enter. Past days cannot be filled in later, so if you start today, your first comparison will be next winter.

The NHS advises seeing a doctor if you think you might have SAD, or if you have been diagnosed and treatment is not helping. If your mood has been low for most of the day for more than two weeks, or your sleep, appetite, work or relationships are affected, talk to your doctor or a mental health professional.

If you are thinking about harming yourself or you are in danger, call your local emergency number now (911 in the US and Canada, 999 in the UK, 000 in Australia, 112 in the EU). In the US and Canada you can also call or text 988, any time. In the UK and Ireland, Samaritans answer free on 116 123, day or night. In Australia, call Lifeline on 13 11 14.