Well, I thought it through and it seems to make sense. My flat is 45 square metres, but what's the point of heating all that space, all night - when it's just my body that needs to be warm? And really, it's the blankets that manage that. So what if I turn the heat off completely?
I tried in a few nights and found I'd wake up with my head cold. So now I wear a cap to bed. Of course, it's cold everywhere when I get up in the morning. But I put on a couple of sweaters and wrap a scarf around my neck until it warms up. Keeping the heat off 8 hours or so every night will surely make a difference on my gas bills.
There's still lots of people in the world who are cold in the morning until they chop wood and build a fire. I'm not so badly off.