Spring equinox. What the return of light does.

In my clinic in Vienna, I have a specific moment in the year when the presenting complaints change. It is around the third week of March, after the equinox. The families who were coming in with sleep problems, mood problems, difficulty with school motivation — the same families, three weeks later, come in with different things. The February problems have mostly resolved. The light has come back.

The spring equinox marks the point at which daylight exceeds twelve hours in the northern hemisphere. This is not a cultural event — it is a physiological inflection point. The circadian systems of children who have been running in the low-light conditions of November through February begin to anchor more reliably. Melatonin onset shifts later. Morning waking becomes easier. The emotional reactivity that was high in February begins to normalise.

This is the biological meaning of spring. Not warmth — light. The warmth follows, but the physiological reset begins with the light crossing the twelve-hour threshold. The child who was impossible to wake in February is, by the third week of March, a measurably different child in the same body. The child who was impossible to wake in February is, by the third week of March, a measurably different child in the same body. I want parents to understand this as a reason to be patient with February and to be ready for March.