The reason why I don't like air matresses when it is cold is simple.

What is an airmatress? A ruber/plastic bag that you put air into. So you have a single air pocket between you and the ground, which conducts the heat from that air pocker faster than you can warm it. Since it is a single, big air pocket, it takes a long time for you to heat it near to body tempurature in the first place, even if the ground wasn't stealing your hard won and well used calories from it. And the matterial itself usually has nothing in the way for heat retention- the only advantage that this would have over a hammock is that ever warmth has stayed in the air away when you get a gust of wind.

Foam pads, on the other hand, are a collection of little tiny air pockets (easier to heat) trapped in a semi-solid material.

Also, the air mattresses sometimes get brittle in the cold, and the moisture that you blew into it while inflating has a habit of turning into ice, which then turns into water, and is very, very hard if not impossible to get out in the woods, adding ot the weight in your pack.

For warm weather, sure, they work, but for the weight, I find a foam pad more comfortable.

Size is another reason that I dislike air mattresses. My BIG, very comfortable and inexpensive Sportsman's Warehouse thermo-rest style mattress takes up less than half the space of an air mattress, is easier to setup and much simpler to repair (although I haven’t punctured a thermo-rest style mattress in years). Even when car camping (truck camping in my case) it is nice to save space and weight.
My air mattresses are reserved for guests at home now, too much of a PITA in the field.

In my case air-filled sleeping pad made a huge difference. Definitely warmer then the closed-cell type.

While this may be true at times, it does not always have to be the case. With proper equipment and proper setup you can be warm in just about any tempature that is survivable. After a few nights where I was not as warm as I would have liked, I decided to fix the problem.There still may be times when the gear I have with me is inadaquate for the current conditions and I have to suffer a little, good planning and preperation has kept those nights few and far between and freak situations where I didn't plan on staying out all night.

Blast:

Sorry I am replying late here. I think everyone mentioned some good and useful ideas. I have very limited experience with air mattresses especially ones that large, which sound to me like a "extra-bed" for the house. My experience is with the older Coleman inflatable style camping mattresses that always seemed to leak even when brand new! I do know that the air mattress will be the same air temp as the outside air, which was already mentioned.

I have noticed one thing everyone has not mentioned, so I will. You state the air was damp from fog. This was a part of the problem that I can see. Fog and heavy rain will dampen the air and even at 40-45 degrees you will become cold. Damp air will permeate and also dampen most clothing. If your sleep clothing was also damp (usually from sweat) and the inside of your bag was also damp, I am certain this all contributed to the fact you were quite cold. I speak from experience as I usually spend one damp and rainy, or foggy night outdoors when camping. I usually sleep quite miserably during a stormy night, and you cannot seem to make a fire fast enough in the morning. The best recourse is of course a shelter system to keep moisture out (e.g. a tent) this way your clothing and bag have a chance to breathe.

I would be curious to know how wet your sleeping bag and fleece cover were when you finally got up and broke camp even if it was in the backyard!

Take care and try again.

Stargazer

I'm with OldBaldGuy on this one. A proper bag, a thermarest, and a closed cell foam pad.

It's amazing how much body heat you can loose through contact with the ground.

Another excellent point was dry a dry sleep kit. Even in temperate weather, I keep one outfit clean and reserved for for sleep (thermals, shorts, whatever). Besides the retarding the "clammy factor" when cold, it really makes a difference in your comfort, and I like to be comfortable when I sleep.

Here is the setup I used for my last snowshoeing trip. We set up the tent right on top of the snow, and I was perfectly warm. When I woke up in the am there was ice on the tent, and icicles inside from the moisture in our breath, but I was fine and warm. It boils down to this: a good tent (this wont work for stargazing obviously), a good bag, and a good thermal pad.

Tent: North Face Mountian 25
Bag: Moonstone Maxima 0deg bag
Pad: Thermarest

Clothing I wear for sleep: Thin set of capaleine long underwear, wool hat. Thats it. In my experience the more clothes you wear in your sleeping bag the more your body has expend energy to warm up the colder you will be. Of course if your bag is not suited for the conditions you will have to wear clothes.

All an air matress does is put a large volume of cold air right next to your body. Makes for a cold night.