Can't help with a remedy but is also a worry of ours once we get the MoHo I know folks on here use alternative heating at night, perhaps a small oil filled radiator. I am sure the more experienced will be along soon to help.
The trouble at the moment is we are on our way down to Spain and ( wa are using diesel rather than expensive electric) the site is charging .48c for 1 kW
So oil filled rad would work in UK . But I don't think here !!
To be honest I seldom put my gas powered only blown air on even at a low setting within 15 mins it's enough but of course it doesn't stay warm.
I have a 500 watt DeLonghi oil filled rad and it's perfectly warm enough,no dry throat and at night if it's chilly just set the thermostat to a low setting to keep the chill off when getting up.
Small,silent,lightweight I find it the perfect solution.
As Gordon said, electric is very expensive in Spain, so gas would be a much cheaper alternative. And it has been really cold in the mornings, approx 2 degrees
Like the idea of a good duvet, perhaps a hot water bottle?