sleeping in the snow..help needed

ok,
i have got a stupid question..
its winter..and assuming you got a waterproof sleeping bag(or using duct taped rubbish bags) and you are using a vapor barrier liner inside your bag.. and no tent, no shelter, no snow caves… is it beter to sleep on the snow in the open or would it be warmer to cover your sleeping bag with snow, like buried inside..
snow is an insulator so perhaps the temp of the snow touching the bag will be higher relative to air temp.? or will i lose more heat due to conduction? what if its very windy? perhaps the rate of heat loss due to convection in strong wind will be more than the heat lost to the snow that covers you which stops the wind??
even if some snow is melted its waterproof and due to vapor barrier liner the sleeping will not be soaked with your sweat.
please comment