I need some guidance/advice.
This season I have slept out 4 nights so far using two different Big Agnes down bags/pad combinations rated for 15 and 20 degrees. Temperatures have ranged from 35F to 47 F with calm to moderate winds, on each separate occassion using hammock, tarp, and large car camping tent. I slept with one bottom layer and one or two top layers along with cap or hoodie. I was not able to sleep comfortably through part of the night due to feeling cold (but no shiver). The only night I was able to stay comfortable the whole night was when the low temp was only in upper 50s. Why am I sleeping cold with 20 degree rated bag?

So you have full length pads under you?

What shelter are you using?

Is the sleeping bag very room inside versus your size?

Does the sleeping bag have a hood?

Most likely bottom insulation.

Sleeping warmly in a hammock can be done, but takes some experimenting.

What specifically did you have beneath you in these set-ups?

On the first night, I used a Hennessey Hammock with BA Zirkel (800 down 20F)and full lengthy mummy isulated aircore Pad (15F rating) temp went to 40F and 20-30mph winds: was somewhat comfortable but slightly chilled around 3AM.

Second night: BA Zirkel, aircore pad, slept on ground with only Tarp, Temp 35F, winds 10-20mph, wool underwear, two layers on torso, hat: Felt very uncomfortably cold most of night but no shivers.

Third night: In a large canvas, wall tent, BA Lone Ranger (15deg,large roomy regtangular bag), 47F, 5-10mph, same clothes as above: Very cold most of night, was able to sleep only from 3-7AM.

Fourth nigh: same as above, temp 57F, no wind, Slept comfortably 8 hours straight, no awakenings.

When I get cold the likely casues are:

Bottom insulation,

Head insulation,

Foot insulation, or

Hand insulation.

I am guessing that you are using an Insulated Air Core. The rating on that pad is ... um.... optimistic. Try putting a Gossamer Gear ThinLight 1/8" pad on top of the Insulated Air Core inside the sleeve.

I switched to a hoodie base layer mostly to secure my hat. No more waking up cold and hunting for my hat. For a side sleepers like me a sleeping bag hood is a cruel hoax.

I use a vapor barrier sandwich on my feet. Liner socks then grocery store produce bags then fleece socks.

The BPL Possum Down gloves are great.

I have a BA Cross Mountain and used to have a Zirkel. The top insulation rating is accurate. The rating for the Insulated Air Core is exaggerated.

I have a BA lone ranger. I have found that the regular air core pad works well down to about 50ish degrees. Beyond that, the insulated air core pad works very well for me. The insulated pad is a little heavier and bulkier though. Also, if the pad you are using doesn't fit the full length of the sleeping bag, it tends to get really cold. I had to switch to a full size pad for that reason. Other than that, I've had no problem staying warm in my BA lone ranger. Good luck!

Joseph,
IMHO I think it's the lack a bottom insulation.

First convince yourself that the sleeping bag is adequate.

Find enough bottom insulation - RidgeRest, Thermarest, generic, to have a convincing R-8, or more. Strap them together so you're not sliding around. Then try the 15° bag. If you wake up sweating, (my bet) go to the 20° bag. If you wake up sweating again you have your answer. Next try the 20° bag with "just enough" Known bottom insulation - say R5.

I do this on the back porch so I have ready access to all possible combinations of pads and bags. Getting a good nights sleep isn't the point. Learning what works means getting up, changing gear, sensing what is cold or hot, up or down, and then adjusting and trying again. You'll get it.

As has been already suggested, lack of adequate bottom insulation and head insulation are likely culprits. You haven't mentioned your head at all.

Another thing to check is whether you had a good meal before going to bed.

Cheers

As a cold sleeper I can relate. However, an BA insulated aircore pad should keep you insulated into the 30s. Perhaps I've had different experiences as the other posting saying it was optimistic but I sleep pretty cold and haven't found it to be the weak link in my systems.

If on the other hand you have the standard aircore, 30's is pushing it and you need to upgrade or pair it with a foam pad. The cheap blue foam pads are a cheap way of extending the range of any inflatable pad to determine if they are your weak link. Put the foam on top of the inflatable one.

For any cold sleeper, these things are very important:

Metabolism: have snacks handy during the night and have a good meal right before bed time. My money is that this is your problem. Even with a good bag, your metabolism may crash during the night without keeping it stoked and leave you feeling quite cold (mine sure does).

Hydration: Gotta digest that food, so make sure you're adequately hydrated. Over-indulging will lead to mid-night pit stops though...

Don't go to bed sweaty/wet, when you chill off, it makes you considerably colder. If your layers are damp, change out for sleeping. Don't over layer until you are sweating either.

Head insulation: even with a well designed sleeping bag, some form of head insulation is highly recommended. Balaclavas are great for the whole face and neck work. Wool hats are good to keep your ears warm. If you sleep cold, these should be on your list for most of the year.

Foot insulation: doesn't sound like your problem but make sure you have dry socks.

Hand insulation: when the temps drop to below 50F consider bringing a light pair of gloves into your sleeping bag.

Avoid constricting clothing: constrictive clothing can lead to decreases in circulation and make you cold. Too many layers can cause this so some find a single base layer to be warmer than piling all the clothing.

Avoid drafts: make sure you spend the time to adjust your hood closures and make sure the draft stopper along your bag's zipper is oriented correctly. If your bag's hood isn't snuggling up well, bring a scarf to fill the void.

Bottom insulation: gear for the weather first, comfort second. When you get all over chill but your top still feels fine that's usually the culprit.

Bag fitment: If your bag is too tight, you may be compressing the loft from the inside. I've had that happen with some slimmer fit bags as I am not built like a twig.

Sleep routines: Realize that some people don't sleep well in the woods until it becomes more routine. When sleeping in the woods you are usually going to sleep earlier and waking up earlier. This is hard to adjust to at home, much less in a foreign area on unusual bedding. Melatonin seems to help many to drift off gently without being a sedative. Benadryl works as well and doubles as antihistamines. Try to integrate some of your home routines if you can. For instance, hot chocolate at 9pm, read a bit before bed or whatever you'd normally do can help you ease into the mood to sleep.

If the cold does come calling:
Grab a snack
Get a bit to drink
Move around a bit and adjust any insulation as necessary
Do not throw clothing on top of your sleeping bag, it just ends up reducing its loft and leaves you with cold spots.

If you are still cold, start doing sleeping bag exercises like crunches or isometric muscle flexing of your big muscles like your quads.

If you are still having problems try carrying a chemical hand warmer to throw in your bag. They work wonders and are relatively lightweight insurance when dialing in your system.

Edited by slacklinejoe on 04/26/2009 18:02:23 MDT.

Joe,

Great and detailed answer.

My quick two cents is that the air mattress might be actings as a heat sink and pulling the heat off of his body.

Air is a conductor of heat/cold and could be pulling away heat and giving him the chill.

A Gossamer Gear Thinlight foam pad or any foam pad might retain the heat that is being drawn off his body.

-Tony

>My quick two cents is that the air mattress might be actings as a heat sink and pulling the heat off of his body.

The Big Agnes Insulated Air-core pad is an inflatable that has a Primaloft core. That significantly reduces convection currents inside the pad, thus the difference in R value. The non-insulated aircore is only R=1 and I only find it useful on the warmer half of the year. My insulated air-core on the other hand has a much higher R value of 4.1 and I've slept on snow many times with it without feeling cool on the back.

The rated temp range for the BA Insul-aircore is 15F vs 35F for the non-insulated aircore. Both of those numbers are the uncomfortable limit for me as I've pushed it below in the past for either.

On top of all the recommendations/suggestion so far I would have to agree with Roger.

If you have ALL your bases covers in terms of insulation and sleeping arrangements, the single biggest differentiator in warm vs cold sleeping from my experiences has been the type and timing of your evening meal.

Nice and big serving, plenty of carbs, and about 30- 1hr before bed time. The theory being that as the body starts to break the meal down (time depends on your metabolism) it exerts energy, this creates heat keeping you warm. It works....try it at home.

Cheers