Why do I always wake up freezing?

Question

I like to go camping in the forest, mostly in summer, sometimes also when temperatures drop to about 0°C/32°F during the night.

I have a three-season sleeping bag (T-comf: -2°C, T-lim: -8°C, T-ext: -26°C), an inflatable sleeping mat (9cm thick, R-value 2.8), and a good enough tent.

My equipment should be sufficient for sleeping outside, let alone in a tent, in 0°C (right?).

Nonetheless, I often wake up in the middle of the night, freezing. Especially, my hips, feet and legs are cold. And of course it is nearly impossible to go back to sleep, once cold.

I have tried wearing warm headwear, woolen underwear and socks inside the sleeping bag, to no avail. Drinking hot tea before turning in has not helped. Clothes, sleeping bag, tent are all nice and dry.

Why do I still wake up freezing? What else I can do to keep warm?

Answer 1

As to why you're still cold with those specs: it happens to me as well, and I think the specs are for the 'average' person meaning not only average amount of body fat but also average temperature regulation (as in: certain people feel cold at x°C, while others might already feel cold at x + 2°C or so, you get the point). So it might be possible that you have e.g. low body fat and hence less insulation and also tend to feel cold quicker. So even though the bag's comfort temperature is at -2°C you still get cold because it's just not a sufficient amount of insulation, for you. I'm not 100% sure this is the case, but it seems a plausible enough explanation; the alternative being that the specs on your bag are simply incorrect and/or exaggerated.

As to what to do about it: first time it happened to me I just put on 2 extra layers of clothing and that was warm enough though not extremely comfortable. After that I got another bag for lower temperatures (something like 5°C lower comfort temp. than the other one) and the was warm enough as well. Also make sure that whatever you put between your bag and the tent floor insulates enough, or sleep raised from the ground.

Answer 2

If you're consistently cold in your sleeping system, then you need to change your system.

An adequate sleep system for cold weather constitutes two sleeping pads: a solid foam sleeping pad underneath of an insulated air mattress.

Your sleeping bag should be rated to well below the temperature you're sleeping in. I don't know who comes up with these comfort ratings, but they always seem very subjective to me. I've got a -10°C sleeping bag that seems barely comfortable enough sleeping in the summer months sometimes (granted even in summer the temperature will drop to freezing overnight in the rockies), but in winter at -15°C I'll find myself sweating in it. What you wear in you bag will affect how warm it is, the best thing to do is wear a single warm base layer inside it. Your bag will feel cold when you get into it, but your body will warm the whole bag if you wear fewer layers in it. If you're getting cold spots, it's because you're insulating parts of your body better than others. Sounds to me like you're wearing more layers on your top than you are on your bottom in your bag.

Before going to bed, you should relieve yourself of all fluids and eat something hot. Drinking a hot drink before bed will warm you up, but it won't keep you warm overnight, in fact a full bladder will make it more difficult to keep warm. Eating a hot meal will warm you up, and put fuel on the fire to keep you warm as you sleep.

Some other items that you can add to your sleeping system may include a bag liner, a vapour barrier, an outer bag, and a warm touque and neck warmer to wear while you sleep and keep the drafts at the neck of your bag at bay.

Answer 3

Here are some other things you can try,

• Fill a water bottle with hot water, wrap it in a t-shirt and put that inside your sleeping bag.

• Don't drink warm tea before you go to bed, as that will increase the chances of having to get out of bed or being uncomfortable all night long.

• On the other hand, eating before bed will give your body fuel during the night.

• Make certain that your sleeping bag fits you properly, as if it is too long there can be an empty space down by your feet that will hurt your ability to stay warm.

• Consider getting a warmer sleeping bag.

Answer 4

A point others haven't stressed enough is that the sleeping bag specs I have encountered are way off, in my experience. My experience is that the sleeping bag should be as warm as possible, under almost all conditions. As a family when we go by car we actually bring our down blankets for camping, one of the most comfortable and luxurious experiences on the trips.

The thing is that a sleeping bag which is too warm does little harm: you can cover yourself only partly, leave it open on the top etc.; many sleeping bags can be opened and used as a blanket, one can have a leg stick out etc.

But a sleeping bag which is too cold really sucks. One can put clothes on, but that basically doubles the dirtying clothes rate and is uncomfortable and probably still chilly.

I found sleeping bags rated in the minus-Celsius range uncomfortably warm only during warm summer nights or in the morning when the sun starts heating up the tent.

The main trade-off is, of course, the sleeping bag's weight, especially if you are hiking, and the cost: Warm sleeping bags that are also light are more expensive.

Bottom line: If one can afford and carry the sleeping bag, it's better to err on the warm side.

Answer 5

Putting together a lot of ideas already covered and adding some tips I've gotten over time. I don't have much natural insulation and get cold easily, so these tips have all been important for me.

1. Ensure you have the proper gear. Sounds like you already do, but maybe need a more appropriate sleeping pad to insulate you from the ever-cold ground. I usually go with egg-crate style foam pads for their versatility and ruggedness. Also take care in how you setup your gear - make sure you will stay insulated off the ground, and have you head and upper body slightly elevated relative to your feet - more blood pressure on your feet than on your head will be precious for comfort overnight.

2. Prepare your body to stay warm over night. This means eating fats and warm foods that digest slowly. Meat, butter, oils, nuts all really help. Not only will the full belly of warm, heavy food make you sleepy, but your body will generate heat as it slowly processes the food overnight. This also means being hydrated but not excessively, and relieving yourself before bed. 'Holding it in' requires muscles to work, which draws energy that could otherwise be used keeping your core and distant extremities warm. Lastly, there is a psychological aspect to this: you will rest better if you're mentally prepared to wake up now and then cold, know your sleep system is adequate, and as long as you're dry and not showing any signs of sever health issues (numb toes that could lead to frostbite, uncontrollable shivering which could hint at hypothermia), you roll over, curl up, and do your best to relax and get back to sleep.

3. Now that your body is prepared to be a heater, and you have the gear to maintain heat, get ready for bed. (This step is important for me as someone fairly lightweight who had the same cold-night problem.) You want to make sure all your clothes are dry, and you want to strip down to the minimum amount of clothing overnight. The latter is for two reasons:

   1. If your sleep system and body are working well, you'll accumulate heat through the night. Too much heat is bad and will make you sweat, and any moisture in your sleep system (whether from sweat, weather, or lack of ventilating your own breath) will in turn make you very cold.
   2. Your body is always trying to stay at a certain temperature. If you go to sleep with all your clothes on and your sleep system, your body will regulate its temperature to its desired state with all aids applied, and when you get up and lose the sleep system but don't add much in the way of clothing, your body's thermostat will be running on the cold side. If you go to sleep with less clothing, your body will be forced to step up its furnace to maintain an acceptable temperature. When you get up and out of the sleep system you'll be glad your body is working harder to keep itself warm (this means burning more energy - all the more reason for the bed-time snack) and that you have more layers to put on.

Lastly, related to all the above points, some other tips that have helped me:

• Take the clothes you removed, and stuff them in your bag (unless that introduces too much moisture to the bag). More insulation & warmer clothes in the morning.
• Warm water up before bed, and sleep with your hot water container (so long as it's seal is reliable). It will stay warmer longer, and heat lost from the water is gained in the sleeping bag.
• Mind your head: your breath needs to be out of the sleeping bag or it will introduce too much moisture inside, and this necessity means at least part of your head will be out of the bag. Have good head insulation handy because of this. That said, still better to try and sleep with fewer clothes if you can handle it. I usually have hats in my bag so I can grab them if I wake up with my head very cold, but I start out with minimal or no hats on.

With all these pointers, I have slept fine many a night in tarp-shelters in the middle of winter (0ºF give or take) using a 20ºF synthetic bag with a 55ºF synthetic bag in that as a liner, putting on a fresh pair of thermal underwear (top and bottom), thick socks, and a trapper hat as a pillow. That can be rough (an actual pillow would help), but I do sleep and even when I wake up once or twice at night from the cold, I can curl up a little more and get back to sleep — before I know it, I wake up cozy to morning.

Answer 6

There are many medical reasons that could contribute to coldness: too thin, anemic, hypothyroidism, poor circulation, tired, dehydrated, not enough vitamin B12, diabetes, lean muscle mass, or maybe you have Raynaud’s. A checkup at the doctor should rule these things out as a cause.

10 Reasons You Feel Cold All The Time

12 Medical Reasons You Always Feel Cold

I would nix most of the clothes, except keep a hat on.

Never wear the day's clothes - if anything, put on tomorrow's clothes.

You say you're wearing wool. Try a synthetic material - polyester - instead. Or silk. Some wools can make you itch, that causes sweating and moisture.

Keep your head outside of the bag: breathing inside the bag brings moisture inside. In this case, your breath is moisturizing your upper body, robbing the lower extremities of heat.

Try using a mummy bag; less air around you to keep warm. Some people find mummies uncomfortable, it takes getting used to.

If you aren't using a mummy, be sure your shoulders are warm; otherwise, you are causing your body to focus on the trunk staying warm, at the expense of the rest of you getting cold.

Try using a softer mat - or a cot. Not for insulation, but for comfort. You may be experiencing hard spots, which cause a feeling of numbness - and cold.

Try sleeping with your head and trunk raised; that will create more blood pressure in the lower extremities.

As for me, I suffer from mild coldness due to joint issues (so, I'm sensitive to hard spots). I use foot warmers - I toss a few into the bag. I also have a Zippo hand warmer (uses Zippo lighter fluid), which lasts about 12-15 hours. These work better with lighter bags for me, since mine keep dying in the middle of the night - I guess maybe because they're starved of air.

Answer 7

Besides all the mostly great advice already here, you can take your down jacket and crumple it into the the bottom of your bag. Once you get into the bag, stuff your bare feet into the coat. This will supply an extra layer of insulation and "fit" for your feet. There are re-usable, lightweight heat packs you can easily carry and place into the coat to give your feet a good, warm start.

It's miserable being cold, which is why I'm just a 3-season backpacker.

Answer 8

I have also had this experience with similar equipment, and found the problem to be the air mattress when the temperature drops to 0°C and below: I have concluded that there is sufficient convection in the air mattress to transfer the cold from the ground to my body.

I have solved the problem by laying a thin foam sleeping mat or folded blanket on top of the air mattress.

I also agree with others who say a sleeping bag rating as comfortable to -2°C does not hold for everyone: I tend to feel colder than others I know with the same equipment and so now habitually over-spec my sleeping bag.

Answer 9

When you say an 'inflatable sleeping mat' is this a sealed foam type one or an inflatable airbed.

If it is an air mattress then that could be part of the problem. Because they contain a large volume of air which can move about they don't provide very good insulation compared to a closed-cell or self inflating foam pad.

If do do use an air mattress in cold conditions you really need an insulating mat as well.

The insulation between you and the ground is at least as important as the rating of your sleeping bag as you lose heat to cold ground much more quickly t han to air and this contact point is exactly where the insulation of the bag is compressed by your weight and least effective.

It is also worth adding that sleeping bag temperature ratings need to be taken with a large pinch of salt as they are often a bit optimistic to start with and what is actually comfortable for an individual can vary a lot from person to person.

Answer 10

An important thing not listed in any of the answers here is to make sure your sleeping bag doesn't let air in around your neck/upper body.

Whether it's a drawstring or something else, try to keep your head area airtight with your sleeping bag. Some sleeping bags, like mummy sleeping bags help with this by giving your sleeping bag natural structure to make this easy.

If you have a rectangular sleeping bag, try to draw its cord tighter and be as low in it as possible. Your head and body give off a lot of heat, which is basically lost in a tent, but if you can capture that in a sleeping bag/pillow that's helpful.

Answer 11

I find that an inflatable mat allows for a great deal of cold from the ground to reach you/warmth from you to be drawn out.

I sleep on an Exped downmat, which although is an inflatable mat, is filled with down feathers.

I used to have the same problem of waking in the night bitterly cold and unable to return to sleep; since using this, I have not had that problem ever. It's a bit of a pricey thing to buy, but for a good night's sleep is definitely a worthwhile investment. And it packs up pretty small too so is nice and light and easy to carry.

Answer 12

I have similar problems with an inflatable mat. With a foam mat, even if it gives slightly under pressure locations, you're still insulated. With an inflatable mat, any pressure location has a good chance of going straight through the mat and touching the ground - and at that point of course you have no insulation at all.

For myself, I combine a Z-Lite underneath and a regular 8mm foam mat on top. The Z-Lite ensures you are well away from the ground, and the foam mat stops you sinking into the Z-Lite (the "egg crate" effect can be uncomfortable). The extra weight is negligible, and the end result is a perfectly-comfortable and perfectly-insulated night's sleep. The Z-Lite is also the best thing ever invented if you're camping on rough/lumpy ground - effectively there isn't competition, because everything else isn't even in the same race. And for bonus points, the Z-Lite also allows some airflow around the tent floor underneath you, so the normal problem with condensation building up under your mat doesn't happen.

Answer 13

I live and play in Michigan. Some of my warmest and best nights of outdoor sleeping have come in -20°C (not including wind-chill) and colder weather. I do sleep warm though.

I have separate "sleeping clothes" which are synthetic long johns. You don't want to wear the long underwear you've been hiking, skiing, snowshoeing or whatever in because you've sweat in them and they are "wet". I don't wear socks because I hate sleeping in socks and my feet never get that cold.

I melt snow and boil the water, filling a 1 liter Nalgene which I put into a sock and toss that in the foot box of my sleeping bag about 45min before I'm planning to sleep.

Eat some warm high-energy food just before bed.

I use two closed-cell foam pads under my bag (rated for -18°C) and cinch the hood part of the mummy bag down around my face. Usually, I will loosen the hood at some point.

Answer 14

I'd try a higher r-value pad or add a pad. There is a fair amount of variation in what people say you should use (in fact checking this post, it was r1.5 to r5). If your 2.8 isn't cutting it for you, try something a bit higher. When you are lying on your sleeping bag, the parts under your body will lose some of it's ability to insulate you. Also be very careful of the ground you are sleeping on (rock is not good). It will also affect how much heat you lose.

Answer 15

The people who have been suggesting sleeping naked and increasing the air flow through your tent might be on to something.

You're going to sleep feeling fine, then waking up in the middle of the night shivering. You're doing things to be warmer, it isn't helping. It might be making it worse by messing with your circadian rhythm. Instead, you might try being cooler. Here's the idea...

Your body temperature rises and falls through the day, peaking in the afternoon and hitting its low point in the wee hours of the morning. This helps tell your body to sleep.

Now you're all bundled up in a little tent with poor air circulation and layers and layers of insulation wrapped tight around you. You go to sleep and the body heat you're radiating is trapped. This builds up until in the middle of the night your body is like "my skin is warm, must be time to be awake!"

You wake up. Your heart rate, slow while you sleep, increases. Blood vessels in your extremities which have constricted to save heat and energy now open up to bring oxygen to those muscles so they can do work. Warm blood flows out of the core, and cooler blood from your extremities flows in. Your core temperature drops and you start to shiver to generate some heat.

(In hypothermia cases, this sudden rush of cold blood from the extremities back to the core can kill. This is why you treat hypothermia by warming the core first.)

Instead, try sleeping with less on to avoid increasing your skin temperature during the night. Socks, and maybe one layer of thermals. Enough to keep you comfortable while you fall asleep.

This is based on an article by the National Sleep Foundation.

Answer 16

Thanks everybody, for LOTS of great suggestions! There are plenty of things here to try (and some are contradictory), and in order to choose the best answer, I'll have to try them all. So I'm going to accept this answer (my own) for now, until I've tried enough of the suggestions to know what works. Then I'll come back here and choose the best answer.

Here's what I will try, in more or less this order:

1. Use a foam mat in combination with the air mattress
2. Make sure I eat well before turning in
3. Have something to eat with me in the tent, so I can get some quick calories in case I wake up
4. Sleeping with more clothes
5. Sleeping with less clothes
6. Trying a warmer sleeping bag

Answer 17

First, your probably sleeping with to much on.

Your sleeping bag looks fine, assuming your mat and tent are fine, then your likely just fighting moisture.

Get naked. Or close to it. At least down to your undies. When you cover up in the sleeping bag, and you ware your cloths, specially day cloths, but even some "night cloths" you are going to sweat a little. Any sleeping bag worth a damn will "wick" that moisture away from you, but if you have closes in between it takes longer. The moisture on your skin means you cool, and thus you get cold.

I know it seems counter intuitive to ware less cloths to stay warm, but give it a try.

Next up is going to be the tent. Make sure you leave a flap open. Not wide open. But air needs to move through the tent to "take away" moisture and humidity. I find the best way to do this is to open a flap "at the top". The hottest of the air gets to move out, and the air flow stays off of you.

Again, I know that seems a bit backwards. Also the opening doesn't have to be much. If done correctly you won't wake up with condensation on the tent.

Finally understanding a single key fact really helps. Again assuming that you don't have a hardware problem (like you mat is too thin, or your sleeping in a swamp) then you don't want the tent to get warm. You want it to stay cool and comfortable. If you sweat, your screwed. In fact, if the tent seems a little cold as you go to sleep that is probably correct. As you sleep your body temperature should warm, and the heat of your body (and others) will make for one awesome space heater.

BONUS: If your tent is to big, you will not be able to warm it properly. Tent sizes tend to be a bit of a joke unless your actually keen on sleeping on top of someone, so it can be a bit hard to tell. But essentially there shouldn't be much more room then it takes for you, and who ever your camping with to lie down. And a little bit extra for maybe a backpack each. Anything more then that and your tent is too big.

Answer 18

I see 2 reasons why this happening:

1. The outside temperature changing all the time. At evening the temperature is higher then in the night(morning). So it's normal that you fell colder during night.
2. It's very much depends on how much tired are you. How much do you walk or work on the route during the day.

As some people already suggested: before going to sleep you have to eat and drink hot water(tea). For example after I'm walking 8 hour with heavy bagpack in a snow I can't even get asleep. It does not matter how warm my sleeping bag is and how much cloth I wear. Only one thing helps: eat and drink something hot.