Camping air mattresses don't insulate well
Although camping air mattresses are great cushions, they are poor insulators.
A sleeping bag on an air mattress works well for most summer camping and in moderate temperatures. Keeping excess heat from building up allows campers to sleep more comfortably.
However, on cool evenings or at higher elevations, campers may find themselves struggling to stay warm, while lying in a sleeping bag on an air mattress.
The large air cavity in the mattress allows air to move around inside, transferring heat from the body to the ground, and warm air cannot build up against the body to keep it comfortable.
On cold nights, a sleeping bag or blanket on an air mattress probably will not insulate enough. The bottom of the sleeping bag will be compressed by body weight and will not be able to trap warm air between the fibers or down. The air mattress cannot trap warm air, either.
This has been an ongoing problem with air mattresses and cold nights: even though campers may be in a very well insulated sleeping bag, the body chills from below.
A tip to stay warm on an air mattress
Camping equipment manufacturers have developed a solution to the problem of compression defeating insulation: the self-inflating pad, which does not compress much and therefore retains its insulating property.
By placing a thin, self-inflating pad on top of an air mattress, the pad will insulate by trapping warm air against the body, and campers will sleep warm and very comfortable, even on a cold night.
3/4 length pad
Even a fairly narrow, 20" wide, 3/4-length, self-inflating pad, which does not extend under the lower legs, can insulate enough to make a camper comfortable on an air mattress on a cool night.
These pads would normally be too small to be used as a sleeping cushion by most leisure tent campers, unless they are children.
Socks and a few unneeded clothes under the foot of the sleeping bag can assist in keeping your feet warmer.
A quality sleeping bag will loft and trap warm air above the camper.
For campers with good circulation, some of the excess heat retained in the trunk of the body will be transferred via the bloodstream to the extremities, and that is often enough to keep the lower legs and feet comfortable.
The self-inflating pad also does not need to be as wide as the air mattress.
The gaps between the pad edge and the mattress edge can even make for more comfort by allowing a bit of excess heat to escape so campers don't get too warm—especially if they are otherwise well-insulated.
If the self inflating pad has a smooth top, the gaps to the sides allow the sleeping bag to rest on the flocking of the air mattress and stay in place better.
Other solutions for sleeping warmer
In a bind, laying clothing between the sleeping bag and air mattress will improve the situation.
In an emergency, a sheet or corrugated cardboard or several sheets of newspaper will also help. These can be placed under the air mattress to reduce heat transfer from the body through the air mattress to the ground.
Air mattress losing pressure on cold nights
A big drop in air temperature between the time of day when the mattress was inflated and the coldest part of night may cause the mattress to become noticeably less firm.
If you are expecting a drop in temperature of 20-30 degrees or more, inflate the air mattress more firm to compensate.
Perspiration and condensation
On a cold night, some of camper's perspiration will pass through the bottom of the sleeping bag and condense on the tufted points of the camping air mattress.
The body perspires even while sleeping, and some of the perspiration will condense on cold surfaces.
Since the tufted dimples of the air mattress are drawn away from the heat of the camper's body, they can become cold enough for perspiration to condense there.
In the morning remove the sleeping bag and let the condensation on the pad or mattress evaporate.
This will keep camping sleep gear in good condition for more camping trips.