Hi, my son turned 2 a month ago. We're currently on holidays where the temperature varies greatly over night (27 degrees Celsius at 7pm down to 9 degrees Celcius at 4am) . At home we have the luxury of air conditioning so we can get his room cold before bed and use warmer sleeping bags, but here we dressee him in thinner sleeping bags but by the middle of the night it's cold and we need to add layers. Is it OK to place a blanket over him now? I don't want to wake him if I don't have to.