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| The Author. Picture Taken by the Author |
Here are some additional thoughts on how to sleep warm
in the winter. For videos on this
subject see my earlier entries to my blog, [Part one HERE] and [Part two HERE], or go to my
YouTube channel at BandanaMan Productions, [Part One HERE] and [Part two HERE].
So, how do you sleep warm in the winter? First, we need to talk about the four ways
your body loses heat
Radiation: you lose up to 50% of your body’s total
heat production from your head at 39o F and 75% at 5o F
if it is uncovered
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| Author’s knit cap and fleece hood. Picture Taken by the Author |
In fall, winter or spring you should always bring a
knit cap or a fleece hood just for sleeping in. I bring a knit cap with me even in the summer,
when I am in Algonquin Provincial Park, because that way I can take a lighter sleeping
bag and still sleep warm. The old wives
tale about wearing a hat to keep your feet warm is true.
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| Author’s sweater. Picture Taken by the Author |
Bring a sleeping layer that you can easily put on or
take off. I bring a sweater with me for
sleeping, because even during the summer it can be cold at night,
sometimes. Because I brought a sweater
as a middle insulating layer for sleeping in, I can bring a lighter sleeping
bag and still sleep warm, just as with my knit cap. I have taken this sweater on many outdoor
adventures. When it isn’t needed, it
goes in my stuff sack and becomes a pillow.
Evaporation and respiration: you should always change
into dry clothes before sleeping, since you lose body heat as sweaty or wet
clothes dry on you. No matter how
careful you are with your layers, your day clothes, particularly your base
layers, will be damp from residual sweat.
I always bring a pair of wool socks for just sleeping in, and in the
winter, I always bring a base-layer that I wear just for sleeping.
In addition, open the vents in your tent, even if it
is freezing, otherwise the moisture in your breath will condense creating frost
or dew inside of your tent. Along the
same lines, don’t cover your face with your sleeping bag, the moisture from
your breath will condense in it, wetting it and chilling you.
Convection: you lose heat to moving air and the
purpose of your tent is to block both precipitation, and wind. A bivvy bag, just like a tent, when added to
your sleeping system, will stop heat loss due to convection.
Conduction, you lose heat to the ground or snow
beneath you. To keep from losing body heat
to the ground, you need insulation in the form of trapped air between you and cold
ground. This insulation can be in the
form of a bough bed or a sleeping pad.
R-value is a measure of a sleeping pads ability to
insulate you from the ground. The higher
the R-value, the higher the insulation it provides. During the spring, summer and fall, you
should use a 3-season sleeping pad, which has an R-value of 2 or higher. In the winter, you should use a sleeping pad
with an R-value of 5 or higher.
R-values are additive, as with clothing layers, you
can combine 2 pads to increase your warmth.
In addition, unlike a sleeping bag, using a higher R-value sleeping pad,
won’t lead to the sleeper overheating.
Also, since women sleep colder than men, due to an average lower body
mass, they will need to increase the recommended R-value by 1: this is true as
well for other cold sleepers.
It was in the 20os the day I camped out and
it got even colder that night, dropping down to the mid-teens. I used two sleeping pads, an inflatable pad and
a closed-cell foam pad, and my sleeping bag was a three-piece sleeping bag set.
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| The NeoAir® All Season™ SV. Picture Taken by the Author |
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| ¾-sized (gray) and full sized (black) closed-cell foam pads. Picture Taken by the Author |
The inflatable pad in the picture above is a NeoAir®
All Season™ SV, which has 2.5” of loft and an R-value of 4.9. In the other picture above, I showed both a ¾-sized
closed-cell foam pad, which I have used for years, and a full sized foam pad,
both of which have an R-value of 1.4. I had
only planned to use one of the foam pads; however, in the end I used them both,
with the ¾-sized pad under my head and torso.
By combining the three sleeping pads, I had a total R-value of 7.7
between the ground and me.
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| The HQ ISSUE Military Style Sleep System, 3 Piece sleeping bag set. Picture Taken by the Author |
The sleeping bag set that I used was the HQ ISSUE
Military Style Sleep System, 3 Piece sleeping bag set, which is two nested
sleeping bags, inside of a bivvy-bag. When
all three parts are used together, the sleeping bag set is rated for minus 4o
Fahrenheit to minus 22o Fahrenheit.
Some other things that you can do to sleep warm in the
winter are:
· Make
sure that you are warm when you get into your sleeping bag. Do some jumping jacks or pushups, just enough
to warm you up without making you sweat.
If you are cold when you go to bed, you will probably be cold all night
long.
· Shake
up your sleeping bag, before you go to bed.
If your sleeping bag has spent the day compressed into its stuff sack, the
insulation will need to be fluffed and redistributed, so that there are not col
spots.
· Since
your sleeping bag depends on you to warm it up and then keep it up to temperature,
use hand warmers or, fill your Nalgene bottle with boiling water and put it
into a large sock, and use them to help get your sleeping bag up to
temperature.
· If
there is room in your sleeping bag, put your next day’s clothes into the bag
with you. You don’t want to have big
pockets of empty space around you, since it is just space that you will have to
warm up.
· Pull
your backpack up over the foot of your sleeping bag. This will help insulate your feet.
· Hydrate,
hydrate, hydrate. Your body needs water
to keep you warm. Obviously, if you drink
too much you will have to get up and pee, however if you drink to little you won’t
be able to maintain your body temperature.
· If
you do have to pee, don’t hold it. Get
up and go or use a pee-bottle, since your body has to spend valuable calories
to keep the liquid in your bladder warm.
· If
there are other people in your tent, sleep close together to share body heat.
Before I crawled into my sleeping bag, I did some
exercises, ate a high energy, protein and fat rich snack before bed and filled
a up a Nalgene bottle with near-boiling water to help me warm up the sleeping
bag. And with the sleeping pads blocking
heat loss to the ground by conduction and with my tent and the 3 Piece sleeping
bag set blocking heat loss due radiation and convection, I felt that I would be
all set for the night.
So how did it go you might ask? It dropped to 15o F by 3:00 am,
that night and I slept very warm. In
fact, the biggest problem that I had was that I started to get too warm by 3:00
am and I had to remove some layers to keep from sweating. The next time that I sleep out in a tent at
15o F, I will do without the bivvy-bag, because the outer sleeping bag’s
surface became damp and so, the bivvy-bag was accumulating too much moisture
and apparently too much heat. Interestingly,
my Nalgene hot water bottle was still nice and warm at 3:00 am and was a real
comfort to curl up with, especially during the early part of the night, when I
was still chilled.
Some other cold weather tips:
· Put
your hiking boots or other things that you don’t want to freeze into your
sleeping bag stuff sack and push it to the bottom of your sleeping bag. I learned this lesson the hard way, some-when
in the late 70s, when I was sleeping in a tent on a frozen lake. I left my leather boots in the vestibule of
my tent, and the next morning they were frozen solid and I couldn’t put them on
until I had thawed them out. Not a great
way to start the morning. Ever after
that, I have put my boots either into my sleeping bag or under my sleeping bag
and on top of my foam pad. Other things
that can stop working when they are cold are batteries, cell phones and
lighters.
· Wrap
your metal liquid fuel bottles with duct tape, since metal fuel bottles can
frost bite your hands in cold weather.
Duct tape will help insulate you from them and it is a good way to store
duct tape.
· Turn
your water bottle upside down, in cold weather.
This way if they freeze, they will freeze at the bottom first.
I hope that this helps you to sleep warm in the
winter, when you adventure into the outdoors.
Sources:
Clarke Green, “How to Sleep Warm
When Camping”, Dec. 20, 2011, https://scoutmastercg.com/how-to-sleep-warm-when-camping/,
accessed Nov. 3, 2017
Keith Erps, “What is R-Value?”, Aug. 2, 2018, https://thermarestblog.com/r-value-meaning/,
accessed Feb. 4, 2019
William W. Forgey, M.D., The Basic Essentials of
Hypothermia, ICS Books, Inc. [Merrillville, Indiana 1991] p 38
“NeoAir® All Season™ SV Review”, https://www.thermarest.com/neoair-all-season-sv#product-info,
accessed Feb. 4, 2019
Valerie Loughney Stapleton, “How to Choose Sleeping
Pads”, https://www.rei.com/learn/expert-advice/sleeping-pads.html,
accessed Feb. 4, 2019
Philip Werner, “Sleeping Pad R Values”, Updated 2019, https://sectionhiker.com/sleeping-pad-r-values/,
accessed Feb. 4, 2019
Peggy Wang, “23 Essential Winter Camping Hacks”, http://www.buzzfeed.com/peggy/essential-winter-camping-hacks#39b0zr9, accessed Nov. 3, 2017
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