Sorry, another outbreak of Stupid Question Disorder.

"What can I wear for my morning zazen that will keep me from freezing, but also from falling asleep again?"
(trousers with lots of spikes and nettles, yes, but apart from that...)

Seriously.
Everything was fine during the short summer when sun and birds were up with me.
Window wide open, universe chirp chirp.

Now it is dark and silent before sunrise, and really cold at the open window.
I don't get a shower or get dressed for work before zazen, I wear pyjamas and a sweater.
In spring, I used to put all the blankets around me, up to the nose, looked as if I was still in bed, only upright.

No wonder I had trouble staying awake some days.

Suggestions??
What do you wear that's comfy? (I don't have appropriate sports dress that I could use.)
What about not falling asleep again? Doing push-ups first????
I've tried prostrations, might work, but dangerous - hit my nose on the floor .

Zazen is a difficult sports.

Gassho,
Danny