For drafty windows, this is always a bit more difficult to speak towards. It's safe to say that you should take your plants away from the window on an extremely cold night, and return them to the sill when that warm sun rises in the morning. This is mainly to avoid cold damage to the leaves and potential shock to the roote. I would also advise not to water at night as a tropical plant sitting in cold, wet soil is bound to get a case of the winter blues, and it may not recover even with the brightest of sunshine.

If you have nowhere to put your plant other than a drafty window sill you could try adding an extra layer of insulation at the window, like sealing off those drafty cracks. They sell all types of tools and tricks at the hardware store. I have also seen people go so far as to buy their plant a sweater. Oh yes, this is a thing. I can’t attest to the success of a plant sweater, but it is one of the cutest and most wholesale things one could do to keep a plant warm during winter months.