You'll stuggle to prevent condensation on single glazing...opening the door whilst you sleep will let give you more air changes and better ventilation ideally you need to cross flow the air through the room but the temperature diff on the window will still be high and therefore still generate condensation.

If you left the heating on a low setting through the night, opened the bedroom door and let's say installed a small vent in the ceiling, through the loft into a soffitt vent that might eliviate the problem.

A de-humifier will help but in these days of energy effciency i would always try other options...

I have seen numerous solutions from substances/products on the glass to sill heating, all generally mask the problem and involve you having to power, wipe or empty something, if you can cure the issue without doing any of the above it is always my preferred route...