Winter Depression (SAD): Making Seasonal Patterns Visible Across Years

The pattern that outlasts a single winter

Every autumn the question comes back: is it just the grey weather, or is there more to it? The problem with seasonal depression is not that it is hard to feel. It is hard to prove. A single bad winter can have a thousand causes: a stressful quarter, a breakup, an infection. Only when the same low repeats year after year at the same time does a suspicion become a pattern.

And no one sees patterns across years from memory. We remember the last winter, maybe the one before, but not the course of four years laid on top of one another. This is exactly where tracking does something memory cannot.

Seasonal affective disorder (SAD) was first described systematically in 1984 by Rosenthal and colleagues in the Archives of General Psychiatry. From the very start, the central criterion was not the severity of the symptoms but their recurrence in the same yearly rhythm. And that recurrence can only be demonstrated across several years.

Why one year is not enough

The DSM-5 lists SAD as a course pattern ("with seasonal pattern") and requires the seasonal link to hold for at least two years, without non-seasonal episodes predominating in the same period. Translated, that means: a single miserable November proves nothing at all. Two or three winters with the same course, by contrast, are a clear signal.

This is not a bureaucratic hurdle but statistically sensible. Mood fluctuates for a hundred reasons. Only when the same dip repeats at the same time of year can you rule out chance with some confidence.

What a yearly pattern looks like

Each single dip on its own would be explainable. Three dips at exactly the same point in the year are a pattern. That is the whole diagnostic trick: not the depth but the regularity.

What you should track

For a robust yearly pattern you need three types of data and, above all, patience:

1. Daily mood on a scale, all year round, including summer
2. Energy and sleep duration, because SAD typically comes with hypersomnia and lack of drive
3. Optional: daylight and weather, to carry the amount of light along as a possible driver

The decisive mistake would be to track only in the bad months. Then summer is missing as a contrast, and without contrast there is no pattern. Track the whole year, especially when you are doing well.

InnerPulse can carry weather and light data along as factors and displays your course as a yearly heatmap in which recurring winter dips show up at a glance. It is exactly this multi-year view that turns individual bad days into a recognizable pattern.

SAD is not just "the winter blues"

A common misconception: that SAD is just a slightly gloomier mood in winter. The typical symptom picture goes further. Characteristic are the so-called atypical features that Rosenthal already described in 1984:

When this picture repeats year after year at the same time and disappears again in spring, that is exactly the pattern a professional looks for.

What often helps with SAD

Treatment belongs in expert hands, but three approaches come up regularly with SAD:

• Light therapy with a daylight lamp (usually 10,000 lux in the morning) is the best-studied specific measure. Tracking shows you over the weeks whether it works for you.
• Psychotherapy, in particular cognitive behavioral therapy with a seasonal focus.
• Medication in more severe cases, in consultation with a doctor.

The advantage of data: you see whether a measure works instead of guessing. How to read effect cleanly from mood data is described in Is my medication working?. Which levers generally act on mood is collected in What acts as an antidepressant.

Important context

• Tracking does not replace a diagnosis. It delivers the pattern; the diagnosis is made by a professional.
• Not every winter low is SAD. Lack of light, less movement and shorter days weigh many people down without a disorder being present.
• It can also go the other way. A small group experiences their lows in summer. That too only shows up across years.

The lead that grows with the years

What is special about seasonal tracking is that the benefit rises with every year. After one winter you have an observation. After three you have a pattern that lets you plan ahead in September: start light therapy earlier, schedule appointments before the low arrives rather than in the middle of it. You no longer wait for the dip, you see it coming.

It is exactly this multi-year view that is the reason to start now, no matter what season you are reading this in. The first data point for the comparison is created today.

Further reading

• Recognizing patterns in mood shows how to read seasonal patterns cleanly.
• 90 days of mood tracking shows from when courses become meaningful.
• The sleep-mood lag is relevant because SAD runs strongly through sleep and energy.
• Chronotypes: owl or lark explains how your daily rhythm shapes light sensitivity.
• How much daylight you really need shows which dose of light supports your mood.
• First description of SAD: Rosenthal et al. (1984)

Related: Track winter depression with InnerPulse