Sleeping bag physics, or how to prove you sleep cold, or how to sleep hot

Trying to sleep in. If it's cold, you can still sleep at a calorie deficit, burning more than normal, but only for so long before you'll wake up "hungry".
Trying to sleep in.

The numbers

The second thing you’ll notice when you’re searching for a sleeping bag is the temperature rating (the first thing might be the cool name, maybe a greek god or native spirit — like cars, don’t be swayed). Worst case: you can expect to survive at that temperature, but sleep will seem a far off thing like melting marshmallows. This is the survival rating. Better case: this is the so-called comfort rating and you’ll probably be able to sleep despite the cold feet. Clearly, there is a big difference between the two temperatures.

Best case: some companies give both numbers. Too often though, a number is thrown around without reference to where it stands on the survival/comfort spectrum and, never, for whom. I would expect (hope) the numbers are for the average male, maybe average female for the women’s bags; but who’s average? the outdoorsman? or, maybe pushing the survival end with a burly “hot” outdoorsman with ample “cold training” — I’ll explain “hot” and “cold trained” and it has nothing to do with melting “marshmallows” or potty training sled puppies.

The materials

Next thing to notice is the material of the sleeping bag, inside and out. I’m a diehard down lover (of the bird variety) because the insulation per weight is incredible and it compresses to itty bittiness. Fast and light gets tossed around a lot. This is as far as I’ll go down that slippery slope. The alternative to down is a variety of synthetic fills. These are almost always heavier and degrade faster. BUT, unlike down that squashes down like a poor kitten sodden in the gutter, synthetic fills retain some of their insulation when wet. I’ve tested this. Really, a wet down bag will suck the heat out of you, literally (to work on evaporating all that water), but a wet synthetic bag will cozy up warm and as soft as wet nylon can ever be.

On the outside, there’s a hierarchy of shell fabrics, just like in shell jackets, from simple nylon up to Gore produced (and competition) levels of waterproof-breathable fabrics. Since there’s a lot more fabric than a jacket, weight accumulates faster, so you probably won’t find fancy three (and four?) ply fabrics (more layers to control the one-way moisture flow: you want water to go against the thermal graduate from your hot body to the cold outside).

In the night, we sweat; under duress, we might sweat a lot. Remember those down bags? You need to get that moisture out before it dampens your insulation. In a tent, there might be condensation on the walls (hot, moist air meets cold outside): open the tent flaps high to let the hottest (moistest) air out. If it’s raining outside, pressure against the tent will undo whatever waterproofness it promised (nothing is truly waterproof — apply enough pressure/time and water will pass though). If it’s feeling crowded, or I’m on a slope, I’ll put my waterproof jacket over my feet (this probably doesn’t help, but it makes me feel better at night).

As a brief aside, you may hear suggestions of putting your wet clothes in the sleeping bag with you to dry off. The extra heat from your body (if you have any to offer) will evaporate that wetness and a good bag will pass that through to the tent. Do not attempt this if you’re tired and cold. It’ll just make you colder, wetter, and probably won’t work anyway. The most I’ll take into my bag at night are damp socks and liner mitts. For the rest, when you stop to make camp, layer up. This is good advice regardless. Stay warm and keep moving. In between layers — usually just after my thinnest insulation layer (a thin fleece) — plaster any damp clothing you aren’t already wearing, usually just the spare liner mitts for me.

To wear or not to wear clothing inside your sleeping bag

Far too often, I hear recommendations against wearing clothing in the sleeping bag. “They’re designed to be slept in naked.” In all the literature I searched, experiments involving people or dummies always involved some clothing. Don’t wear something that will block heat and moisture flow, but extra insulation is still extra insulation.

Men vs women: more than just size and shape

Not only is the average man larger and heavier than the average woman (meaning more heat production which goes with volume, but also faster heat loss which goes with area), but we physiologically manage our heat compromises differently. Women are far faster to sacrifice the extremities to keep the core warm (cold feet sound familiar?). Men, even accounting for higher metabolisms given their size, continue to metabolize higher relatively when they sleep. How often you expose yourself to cold, awake and sleeping, can increase your tolerance to sleeping cold and raise your sleeping metabolism (so does eating a chocolate bar in the middle of night, teeth be damned). This is cold training. Don’t ask about the nearly naked peddling rectal temperature experiments — the Norwegians are nuts.

Here’s a little math. The insulation, I, of a sleeping bag is measure of the steady state (no net heat flow) temperature gradient it can maintain over a certain volume divided by the heat source within the bag (you): I ∝ Δ T A / W.

Insulation increases with the loft of the bag (notice how a good winter bag looks like there’s already somebody inside of it when it’s laid out). Ideally, the (outer) area is minimized around the person while maintaining a continuous hefty loft of insulation around them: get the right size of bag.

A “hot” man metabolizes 50% more heat than a “cold” one and 33% more heat than a “hot” woman; a “hot” woman metabolizes 30% more heat than a “cold” woman and 10% more heat than a “cold” man. All these percentages translate proportionally to tolerable temperature ranges. An at-home sleeping skin temperature is around 30°C; a tolerably colder one is 25°C. A summer sleeping bag rated to freezing for a “hot” man will only give the equivalent insulation at 15°C for a “cold” woman (where “cold” could just mean small).

Men or women specific bags never fit me right: there’s always too much room around the core. To fill that space, I stuff every over down insulated item I carried (usually just a down jacket, but sometimes two of them). For truly excessive space and the remarkably strong, two sleeping bags, one inside the other, can work; note, there’s no point in two bags if the fit is tight enough to squeeze away the loft that either would deliver on its own.

Sleeping side by side shares heat, even if it’s not close enough to compress loft. If you squeeze tightly, the inside temperatures will try to equilibrate — so your tent partner can share some of his/her hotness.


Life is an Adventure

Whether it’s three parts internal and seven outward or vice versa or all or none of one or the other, when we truly live our lives, it’s a total adventure. 

Taken during my stay up Cerise creek.

I was watching a climbing video (we climbers do that a lot), a different style of climb however involving the solo bike crossing of Kyrgyzstan to attempt first ascents of many of its peaks.  Watch it if you have time and consider his challenge upon reaching the end of the road. I couldn’t help comparing what I’m doing with what he did (somewhat like comparing my physics self to Feynman or Einstein, but I’ll do it anyway). Writing is hard and scary, not only because it doesn’t pay (yet), but the process itself has to be more honest than I may possibly be capable of, and even if I try and struggle and suffer, I may still fall short and fail. Choosing to take this challenge against a backdrop of mountains may be because they’re a familiar setting for challenge and inspiration to me (not to mention a fairly universal symbol of them too). Are our inner adventures so different from the outer ones? Don’t they ultimately reduce to the same thing anyway?

Hut life

A duffy lake rd hut that will remain nameless to aid its needed anonymity due to a dubious legal status.
A duffy lake rd hut that will remain nameless to aid its needed anonymity due to a dubious legal status.

After another week in the backcountry, I’m starting to settle into the day-to-day of writing in a mountain hut. First, leaving the city is exhilarating (as much so as coming back to it and hot showers, or more). The roads are familiar: the logging roads peeling off into one valley after another recall memories of their twists and turns and the peaks they promised. By nearly forgotten dreams of summits not yet reached call out after more than two years away and two more years of lazy cragging. The trailheads are dubious pullouts that look far more promising during the weekend (and during the ski season) full of cars. The approaches range from open logging road + well maintained trail (eg. to Keith’s hut) to a mild bush whack up an overgrown logging road (not sure I’m willing to strike out on into full on bush whacking for rumours of a hut).

The huts are amazing. Log + plywood buildings, insulated and cozy, with a wood stove for heating in the winters, an elevated level for sleeping, and this place even had a two-sleeping-padded ski couch (see the ski tips peeking out of left of the couch). At the very least, when using a mountain hut, leave it as you found it — no, always aim for better1.

Morning: wake as far after dawn as manageable given the lack of curtains (far better than a tent!); brew coffee2, breakfast; think/stare into space and take the odd notes, reading when frustrated/bored (good nook). Lunch (bread, butter, peanut butter is roughly equal portions), more of the same; soak dinner of dehydrated goodies so cooking is faster. Cook dinner, burn paper waste, eat, read, think, read, etc, until nightfall or earlier. Sleep — oh wondrous sleep and dreams! Seriously: averaging 10-12 hrs up there must be good for creativity.

After another weekend in the city, it’s back to the backcountry on Monday!

1. The horror of molding dishes and heaps of semi-decomposed TP didn’t last around the last hut I visited. I’m extra glad to be using a wood burning stove to burn through the evidence.

2. Habit has become be taking fatty greek yoghourt to finish after the hike in, leaving a pot to steep coffee in; then, using a homemade ‘sock’ cotton filter, pour/filter and presto! coffee. Said yoghourt pot doubles as a garbage receptacle for the hike out.

Friendly tree

I’ve developed a habit of personifying houses, first in Vancouver then again in Cambridge, and then trees, and, passing them, they would irrationally cheer me, like seeing an old friend, even if I did pass them twice daily on my commute. It became a game of looking for them only on the days I especially “needed it”, and, when that didn’t come often enough, on the days that still felt special.

Top, Van cheering house; bottom, Cambridge house.

On the hikes up Cerise Creek last week, I made friends with this tall leaning tree alongside the logging road section of the trail. No cheering necessary for me of late, but he does widen my smile as I pass.

He’s crooked but smiling.

The escape is real!

Matier as seen from the hut. The long snow ridge is roughly northward and a lovely hike (mostly) from the hut to the start of the gnarly rock bits -- highly recommended.
Matier as seen from the hut. The long snow ridge is roughly northward and a lovely hike (mostly) from the hut to the start of the gnarly rock bits — highly recommended.

Before heading out, admittedly, there was a lot of stress. How much food will I need? Can I carry it all? What about weather, animals, bugs, loneliness? And how much TP (=toilet paper) does a person need eating primarily a reconstituted diet (of goodness, thanks again mom!) and drinking oh so fresh water straight off the glacier? Well, I’m back to refill (mostly for lack of TP, aka, whatever I brought, the answer was more) in Pemberton.

It’s not stressful up there. There’s no alarm, just the sun streaking through the peaked windows at dawn and beckoning with the reflections off the glacier beyond. There’s a carefully trodden path to the outhouse, to the stream where I get my water (two streams and two muddy patches over to the coolest water straight from that same glacier above), that I’m taking in flip flops (somewhat flippantly, giddy but with no shortage of respect) at a fast clip to outrun the mosquitoes and biting black things (flies, no-see-ums, something like a midge…). Every second or third day, whenever I feel like it, I take a hike/scramble/climb to somewhere new (Vantage has a great ‘vantage’ of the northeast side of Matier; then the 2km long snowy arm of Matier reaching northward offered another day’s escape; next: Duke? Twin One lake?). 

There’s so much freedom in going it solo in the wilderness. The first few days were unreal. It truly hit me when I was hiking in past sunset and my nerves were tweaked against upcoming night but the forest glowed in this amazing light and the sun just never seemed to set. I felt confident finally and giddy with the freedom it delivered. 

For the writing, the biggest change has been the time and space to think. People are wonderful at letting me work when it looks like I’m actually working (aka, writing actively). But writing a novel, it turns out, required ample time just spaced out. For me, there can be no better place for that than staring down a glacier, familiar as an old friend and yet always mysterious.

A few more days of this, then a proper people-filled recharge in the city next week. Mountains to all!

e-ink writing 201: NST 1.2.1 rooted with usb host

May 31, 2015: I have updated the root + usb host enabling once again! Please visit my new blog site for the newer instructions and a few awesome app recommendations that I’ve missed all this time.

La Push's 2nd Beach all to ourselves as the sun sets.
La Push’s 2nd Beach all to ourselves as the sun sets.

With mysterious charging issues I decided to try upgrading my Nook Simple Touch (NST) to the latest OS (1.2.1) before rooting. Now there exists a graphical program to root the Nook, making it easier than ever to do. NookManager is loaded onto a microSD that the Nook (upgraded to 1.2.1) will boot from. A few straightforward prompts later and the Nook is rooted (with optional backing up, advised as always).

Steps to re-root:

  1. Restore Nook to factory settings, through Settings in the Nook OS, or using NookManager’s Restore (“Restore”).
  2. Boot with NookManager on microSD in the Nook.
  3. Optional: Backup.
  4. Root.
  5. Next: to get the keyboard working again. Connect via ADB as in my instructions in my first post (e-ink writing 101), to install USBMode 1.7 and Jota (this time I installed from the apk directly), and to push the modified uImage and uRamdisk binary files.

So far, the keyboard input to Jota is smooth. Saving is mysteriously only to microSD card, but that’s alright since I just repurposed the install card. The charging issues are at bay but possibly that’s because I threatened to replace my Nook with a new one.

Big tree in Hoh Rainforest.
Big tree in Hoh Rainforest.

Plans are meant to be changed

Great Sand Dunes NP, 2013. Looks like a painting but I assure that it’s real.

After a few days of intense research into a late spring tour of the SW National Parks, just two days into the road trip and the heat had us Canadians fleeing northward from the forest fires in Colorado and the intense heat of Utah. That brought us early in Seattle with time to tour the Olympics, the Cascades and surrounding area. 

As planned.
As executed (so far).

Home-sewn rain poncho

Photo on 6-7-13 at 3.01 PM #2
I bought waterproof-breathable vinyl-coated nylon fabric in Vancouver at a shop specializing in fabric etc for outdoor gear, Outdoor Innovations. Finally, many years later, I’ve sewn in into an extremely lightweight poncho (See & Sew B4266 with a longer back). Sewing with this fabric was both wonderful and awful: wonderful for keeping a fold briefly pressed just with my fingers but awful for being so thin that I had to hold it until tension to help the sewing machine feed properly. Worth it and I’ll definitely look for more projects with it (tarp tent maybe?).

For waterproofness, I tested the fabric against my North Face Hyvent fabric jacket (unfairly really — hyvent is roughly three or more times heavier than my poncho fabric) by sitting a cup of water in a synched pocket of fabric. After half an hour, the lightweight fabric let through a small puddle of water while the hyvent was just starting to think about sweating (not damp feeling quite). Still, after seam sealing, I figure since the poncho can sit above the backpack straps — the pressure of the straps makes water leak through my hyvent jacket — it may still keep me dryer in a long hike in the rain. Reports to come after some in the field testing!

…and other projects including a stretchy jean jacket (so comfy! but I’m not sewing with thick and stretchy fabric until I forget how annoying it was to work with — worse than silk), my first ever shorts (so cute! again stretchy fabric is more comfy) and a somewhat more formal dress in stretchy gray that let me skip the zipper (not sure when I’ll get to wear it though!).

sewed 2

Procrastinations (aka I’ve been busy!)



It’s been a whopping month+ since I’ve blogged and I’m back to recount the multitude of diversions.

1) Vipassana retreat. I waffled over writing a post about my meditation retreat, before, during and after it was over, but finally, in all seriousness, a blog is no place to share that (for me anyway). For those interested, by all means look at  for locations and specifics about joining a retreat, or for publications and lectures (many free) about it. 

2) Sewing! The photo montage is only a selection (maybe half) of my projects in May/June — forgive the poor photobooth quality. The missing ones are mostly missing buttons since I only got the crazy glue to fix the “automatic button hole foot” recently. More photos to come with buttons. Every one of the dresses/shirts above come from the “Built by Wendy Dresses” basic patterns with personalized modifications/embellishments. These showcase various projects from the book. I highly recommend them since the fitting is casual and loose and easy to adjust for a nice fit. I have a few jackets from her Jackets & Coats book to showcase after more buttoning. 

3) Road trip planning!!! In just over two weeks, my mom and I leave for a road trip tour of the National Parks in Colorado (en route) and Southern Utah covering in three glorious weeks: Great Sand Dunes NP, Black Canyon of Gunnison NP, Island in the Sky of Canyonlands NP, Arches NP, Needles District of Canyonlands NP, the Valley of the Gods, Natural Bridges NP, Monument Valley, Navajo NM, the Page end of the Grand Canyon (perhaps dipping into Antelope Canyon), the Grand Canyon NP North rim, Zion NP (oh how I love that place since climbing there last spring), Bryce Canyon NP, culminating in a multiple night leisurely exploration along Hole in the Rock Rd of Glen Canyon NP before driving up the Seattle. After much frustration faffing in google maps (it’s buggy after ~10 stops in map planning),  I discovered this wonderful road trip optimizer to plan our route. After inputting coordinates, it ordered our stops to minimize driving time, and spat the route out direct to google maps for saving/directions/etc (5698km in roughly 2 d, 22h, 31m).



Besides that, lots of Heroes reruns (while sewing), reading (for fun, reviewing and my own novel too), and house renos still (deck work is more fun that installing toilets/cupboards/etc). Next step is packing for the road trip and my entire summer in the mountains. In just two weeks, my new home will be my roving tent, my mom’s hyundai (on loan all summer! have I mentioned how awesome my mom is lately? I will again, surely) and my hopefully-trusty wood-burning usb-powering Biolite stove keeping me writing. 

Thoughts about MIT and Boston

Waiting for 4th of July fireworks in the rain on the roof of the climbing building at MIT.
Waiting for 4th of July fireworks in the rain on the roof of the climbing building at MIT.

All the terrible news about Boston and now MIT hitting far too close to home killing a campus security guard that I took hiking on a winter school trip just a few months ago, makes me reminiscent about the good times there.

I miss Cambridge and MIT and all the friends I made in my two years there. They were my introduction to US living and one of the highest reputed Universities in the world. Cambridge is a beautiful town full of ivy covered stone masonry, winding roads that are a heartache to navigate even with GPS (but still oh so much easier than across the river in Boston!), and some of the friendliest people I’ve ever met. Random conversations on public transit were kind and insightful (in Van, mostly only the crazies talk) and I even made a good friend through a repeat ‘hey, that jacket’s from la cordee in Montreal!’ introduction before recognizing each other.

White Mountains in the fall.cannon
White Mountains in the fall; an “easy” climb on Cannon.

I’m an outdoor fanatic and I got involved in MIT’s outdoor club, MITOC, and after I got used to the almost anal safeguarding and liability wavers (ah, the USA) compared to my old club, the VOC at UBC, I found a club with so much energy to teach and share, to spread the love of the outdoors and how to safe in them. Like a good west coasters, I mocked their so-called mountains but, honestly, the Whites are gorgeous. In the fall, the colours are astounding and the peaks, for the little that they rise above sea level, offer ruggedly rocky, exposed and weather beaten summits that’s hard to beat. And the rock climbing walls could be as epic as the best out West!

MIT was not the stuck up academia that I thought it would be. My group was composed of some famous physicists but they were down to earth and friendly. Our lunches were notorious for going on forever with joking and ridiculous tangents (that sometimes led to good ideas!). The campus was connected, physically, so one could literally walk from engineering, through physics, to chemistry, math, and architecture with a little zig zagging up and down the levels. 

Some people ask why I left physics, how I knew, what I had planned. In the back of my mind I always intended on leaving physics — I just had to get that phD first for some reason. I hadn’t intended on the postdoc but I’m so incredibly grateful I did it anyway. 

I’m sending positive thoughts and memories about MIT, Cambridge and it’s big friendly neighbour Boston to all. I hope we get through these rough times quickly.