I often hear people jokingly say “Aaah I have a touch of the SADS”. We moan about the greyness of winter, the long nights, the short days. We say our mood is ‘dark’, we hope for light ‘to be shed’ on things, we long for something to brighten our mood, we talk of Winter dreariness. We say it affects us, it’s built into our language. But does it really affect us?