a hot water bottle.....nah being serious...you get into a down bag cold...you stay cold...you get in warm and you stay warm....try wearing thermals to bed....
I have a 750g macpac bag and sleep really warm with a cheap warehouse bag liner...for really cold winter nights I used to have a winter weight single bed sheet sown into a sack and used it as a liner...bulky and heavy but very warm,there are polarfleece options now..a liner boosts bags rating by heaps as it keeps the warm in close to you....it sounds like you are cold to begin with.......a hottie is or course far too heavy to carry BUT a drink bottle of warm water poked into sleeping bag just before you get in and taken out soon afterwards might help get the air inside bag warm,zipped up it will stay warm..take bottle out so you dont roll over and wet the bed!!!!
a sleeping bag cover like the old japara ones the defence force had (mine must be 50 years old) also boost warmth by huge amount...I didnt realise how much by untill got sick of my mate freezing in his cheap lightweight bag on week long trip so gave him mine to use....I felt the cold a little more afterwards...again it must be the trapping of warmth and the cover stops moving cold air from robbing it from you.
Bookmarks