Why don’t humans hibernate?

Some days I wish I was a hedgehog. Or a squirrel – with a nice bushy tail to wrap around myself while I curled up to sleep for the winter. I would sleep and sleep and sleep, only popping out occasionally for a bite to eat. Sounds wonderful!
Hibernation sounds like heaven right now. I am sooo tired. And the tiredness seems to be there, no matter how much sleep I get. Not that I’ve ben getting much sleep (usually six hours a night, seven if I’m lucky), but that’s normal. And usually I’m not this tired. I blame the weather! It’s dark when I get up (and when I leave the house) and dark again by home time. Currentlyit’s at least light when I get off my train in the morning, so I at least get to travel the last few metres to work in the light, but soon it will be dark then too. And it’s cold. So, so cold. Despite the fact that it isn’t officially winter until 22 December(!!) according to my calendar. Remind me why humans don’t hibernate…