Spring approaching. What the returning light does to children.

March is the month when the light returns in a way that the body can feel before the mind has processed it. In Vienna, it arrives usually around the second week — the specific quality of March light, lower in the sky than June but already longer than December. My children notice it before they can name it. They start staying outside later. They seem more interested in the world.

The mechanism is specific: the March light is increasing in both duration and intensity, and the circadian system — which uses light as its primary input — begins to adjust the timing of melatonin production, the depth of the morning cortisol awakening response, and the general level of afternoon energy. The body, in March, is running a different programme from January.

The circadian system is not metaphorical. It is a physical mechanism in the suprachiasmatic nucleus of the hypothalamus, driven by light signals from the retina. The March light signals are different from the January light signals. The body registers the difference and responds. The response is the energy. The energy is real. This is the specific thing that produces the change. The change comes from the practice. The practice comes from the decision to try it once, this week,