Since chronic restriction of sleep to 6 h or less per night produced cognitive performance deficits equivalent to up to 2 nights of total sleep deprivation, it appears that even relatively moderate sleep restriction can seriously impair waking neurobehavioral functions in healthy adults. Sleepiness ratings suggest that subjects were largely unaware of these increasing cognitive deficits, which may explain why the impact of chronic sleep restriction on waking cognitive functions is often assumed to be benign. Physiological sleep responses to chronic restriction did not mirror waking neurobehavioral responses, but cumulative wakefulness in excess of a 15.84 h predicted performance lapses across all four experimental conditions. This suggests that sleep debt is perhaps best understood as resulting in additional wakefulness that has a neurobiological “cost” which accumulates over time.
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Five years ago I purchased the PragmaBed Simple Adjust Head & Foot bed frame. It has proved to be an excellent purchase. I can’t think of any way to improve it.
When I went to college, I spent the first year in the dorms. The bed frames provided by the university were Twin XL, so I showed up with a Twin XL mattress and bed sheets. In the subsequent years, I’ve replaced that mattress and all the sheets. But never all at once, which means I’ve just continued to buy Twin XL sized things. That was still the case when I bought the PragmaBed frame. I would be just as happy with a Twin sized bed. I’ve never been convinced of a need for something wider, but one of the things that attracted me to the PragmaBed was that, if my mind was ever changed, I could simply buy a second frame and attach it to my existing one with the attachment brackets offered by PragmaBed. Instant wide bed frame.
The legs of the PragmaBed collapse and the body folds in half, making the frame easily movable by a single individual. This is a thing I value, despite moving my bed infrequently. The frame is made of steel, with a powder coating that is reminiscent of a truck bed lining. It is a durable package that I expect to last for many years to come.
PragmaBed offers brackets that allow you to attach a normal head- or foot-board to the frame. I’ve never been sure what functionality a head- or foot-board is supposed to provide, so I don’t have these brackets. My previous bed frame also did not have a head- or foot-board, and somehow I always managed to sleep in it without falling out.
The head of the bed has a ratcheting mechanism that allows it to be raised, like a hospitable bed. This is great for lounging – I’ve never felt that the functionality offered by a couch justified the real estate required by a couch, but now my bed is a couch – or when injured. The foot of the bed can also be raised, though not as high as the head. I’ve never actually raised the foot. I imagine it is useful if you’re trying to reduce swelling in your lower legs or feet.
The legs raise the platform 13” off the ground. I keep four 40-quart Iris Store and Slide boxes underneath it. One holds my spare pillow and linens, one holds spare towels, one holds all of my pants, and the last holds specialized out-of-season items and a few miscellaneous items like hats.
I’ve used these same containers for eight years now. They fulfill their purpose admirably, and are the right size for my use. I’m not tempted to buy another spare set of sheets, because my spare sheets box is full. If I want to buy a new pair of pants, I first have to get rid of a pair of pants so that I have room in my pants box.
While in Yellowstone earlier this month I ripped my Cocoon Silk Mummy Liner. I had originally purchased this in 2005, in an attempt to eek out a little more warmth from the sleeping bag I had at the time (a Snugpak Special Forces 1 purchased from TAD Gear). The claim was that a silk liner would add around 10 degrees Fahrenheit to the sleeping bag rating. My experience was that it may have contributed 10 degrees to the survivability, but closer to 5 degrees to the comfort. Still, I continued to augment my sleeping bags with that same liner for the subsequent 14 years.
I find the primary benefit of a liner is cleanliness. Sleep systems get dirty – dirt, oil, sunblock, etc. all get transferred from your skin to whatever you’re crawling into. It is much easier to clean all of that out of a liner than the sleeping bag itself. A sleeping bag worth purchasing is an expensive investment, and I think liners can help extend the life of that investment. I’ve also carried my liner by itself when travelling internationally. It functions well when the guest house doesn’t provide sheets, or when their cleanliness is questionable (silk resists bed bugs and dust mites), or for a little warmth during unexpected stealth camps.
A liner may be purchased in a number of different materials, but the characteristics of silk make it the only material that interests me. It is easily packable, thanks to its low weight and ability to be compressed. It is breathable, quick drying, and comfortable against the skin. This last property is particularly important in a liner. I find synthetic materials like polyester and microfiber can be scratchy or grabby, which is unpleasant in bedding – especially in subfreezing temperatures when there is no moisture in the air.
So when the Cocoon liner ripped, I knew I would immediately replace it with another silk liner. I would have been happy with an identical replacement from Cocoon, but I decided to look around and see if there was anything new worth considering. I settled upon the Sea to Summit Premium Silk Travel Mummy Liner.
Sea to Summit makes their liner out of a ripstop silk, unlike my original Cocoon liner (though Cocoon does now offer a ripstop variant). It uses a thin shock cord and cord lock to cinch the hood, where my Cocoon liner offered a simple silk drawstring that was annoying to use (causing me to never cinch down the hood). But what I found most intriguing about the Sea to Summit offering is that it featured stretch Lycra panels down each side of the liner. If you move around at night, liners have a tendency to get somewhat twisted up. The silk itself has little stretch. The combination of these two characteristics is what led my liner to finally rip. The rip occurred along one of the side seams while I was turning in my sleep. I think that the Lycra panels on the Sea to Summit liner will reduce the likelihood of this happening again.
My initial impressions of the Sea to Summit liner have been positive. The silk is comfortable, though not as soft as the Cocoon liner. This may partially be due to the 14 years of wear placed on the Cocoon silk, but I suspect the presence of the ripstop grid on the Sea to Summit silk is a more significant factor. The dimensions of the two are pretty much the same. The Sea to Summit footbox and hood are both a little smaller than the Cocoon, but I don’t think this contributes to any practical difference. I’ve tried sleeping in the Sea to Summit liner and so far the stretch Lycra panels do seem effective at reducing the twisting and binding that I’ve come to expect from my silk liner. I purchased the new liner in the eucalyptus green color, which is acceptable, but I much prefer the greenish brown of the old Cocoon. The Sea to Summit liner weighs 142 grams (5 oz). This is slightly more than the 114 grams (4 oz) of the Cocoon, but close enough for me not to care. These weights are for the liners only. Both liners come with small mesh storage bags, which I never use.
Flat sheets with folded corners are functional mattress covers, and make every flat sheet you own twice as useful as it was before. I believe elastic-bound, fitted sheets are just a conspiracy created by the bedding industry to get us to spend more money.
Linen is my preferred material for bedding and towels (except for travel towels, where I still prefer synthetic). When purchased through normal channels, it can be prohibitively expensive. I cut out the middlemen and acquire linen directly from Eastern European makers on Esty, where it is much more affordable. My duvet cover is from Belarus. My sheets and pillow cases also hail from Belarus. My preferred towels are from Lithuania.
Last year BoingBoing linked to a video featuring delta waves produced by the idling engine of an ice breaker in the arctic. I found it to be a useful tool, so downloaded it for offline access. Later, I decided I wanted the audio on my phone. The video is a 10 hour loop, resulting in too large a file for mobile storage. To turn it into something reasonable for a phone, I used ffmpeg to extract the audio, chop it down to 3 hours, and add a 10 second fade on either end.
$ ffmpeg \
-i ~/library/video/web/White\ Noise\ Sounds\ of\ Frozen\ Arctic\ Ocean\ with\ Polar\ Icebreaker\ Idling\ -\ Creating\ Delta\ Waves-gpW7iYfuGDU.webm \
-ss 00:00:00 \
-t 03:00:00 \
-af afade=in:st=0:d=10,afade=out:st=10790:d=10 \
I then added ID3 tags from the metadata of the original video.
$ id3tag \
--artist="Relax Sleep ASMR" \
--song="White Noise Sounds of Frozen Arctic Ocean with Polar Icebreaker Idling - Creating Delta Waves" \
The result is a 165 MB file of loopable delta waves, perfect for drowning out the world.
The original video has since been deleted (a reminder to download any data that you find to be useful), but is available at the Internet Archive.
The above spectrogram of the file is produced by Spek.
One component of optimizing for sleep is selecting the right tools. Back in 2010 I went looking for a replacement for the stereotypical feather pillow. Feather pillows work well enough when new, but degrade over time and are impossible to thoroughly clean without damaging them. This limited service life is suboptimal, and I assumed there must be a better solution out there.
I settled on buckwheat hulls. I reasoned that these would be easy to replace, which meant the life of the pillow would be determined by the shell rather than the filling. That the hulls were easily removed also meant the pillow could be washed. These two factors addressed my primary complaints against feather pillows.
I already had a zafu filled with buckwheat hulls, so I had some experience with the material that made me think it would work well for sleeping. Buckwheat hulls are lightweight and springy, making them easy to adjust to the contours of the body. The shape of the hulls means that, even under load, they do not compress flat, but instead leave a path for the movement of air. They are hypoallergenic and aren’t a food source for anything, which minimizes the probability of dust mites or other bugs taking up residency.
About the only negative thing one can say about buckwheat hulls is that they are loud. This was never a concern with my zafu, but I was worried that the noise would be unpleasant for a head pillow that I was trying to sleep on.
The solution to this was provided by a (now defunct) company called Serenity Pillows. They offered a patented dual-chamber pillow, which was filled with buckwheat hulls on one side, and a sheet of felted wool on the other side. By placing your head on the wool side you retained all the benefits of a buckwheat hull pillow, plus the temperature-regulation of wool, while the wool also muffled the sound of the hulls. I was sold on this idea as soon as I saw it.
Serenity Pillows offered two sizes of this dual-chamber pillow: one that we in the Western world would call a normal sized pillow, and a smaller version named the Shambho. The smaller size was about 16” x 10” (with a variable depth, depending on the amount of hulls you added or removed), which they claimed was closer to the traditional size of buckwheat hulls pillows used in Japan. I had never questioned the size of a pillow before, but when presented with this choice I couldn’t come up with any rational argument to support the larger size. I purchased the Shambho.
I’ve been sleeping on that same pillow for close to a decade now. It is never too hot or too cold. The amount of hulls can be adjusted to user preference. The shape of the pillow can be molded to support back or side sleeping. And I’ve never thought of a reason to want a larger size. It’s the perfect pillow.
I wash pillow cases regularly, and the pillow shell itself once or twice per year. This is a simple matter of dumping the hulls into a bucket, removing the felted wool sheet, and tossing the empty shell into the laundry machine with a bit of bleach.
Initially, the unusually small size of the pillow did make it difficult to find pillow cases, but I found that you can search for “toddler pillow cases” and find a plethora of appropriately sized (around 20” x 14” flat) options. Or you can have them made. I prefer linen – as in flax – for bedding, which I acquire from the large number of Eastern European sellers on Etsy. Since these products are usually made to order, I’ve found you can just send them the proper dimensions and they’ll sew up whatever you want. I always request a pillow case with an envelope closure, since the non-closing pillow cases more common in this country are dumb and their existence can only be justified by laziness. For this style of pillow case, 18” x 14” is about the right size.
At one point a few years ago I heard that Serenity Pillows had gone out of business, and was disappointed that I would never be able to replace this pillow – until last year, when I discovered a company called Sachi Organics had purchased the designs to both sizes of the Serenity dual-chambered pillows. They sell both the Shambho and the larger model Rejuvenation.
At the end of 2017 I purchased the Sachi Shambho during a sale at one of their dealers. It is identical to the original pillow, except for the tag. The small size of the Shambho makes it easy to store, so I was able to justify to myself the purchase of a second pillow both as a spare for guests, and against the day when the original Shambho must be replaced (if that day ever comes – today it is as good as new, but for some discoloration from use). I also purchased a replacement wool sheet for the original pillow. On top of its comfort, the serviceability of the pillow – that you can rejuvenate it by simply replacing the buckwheat hulls and wool – is another factor that attracts me to the Shambho. I expect I’ll be sleeping on the same pillow for at least another decade.
Piotr Wozniak, the author of spaced repetition software SuperMemo, has a lengthy treatise on sleep, based on his long running research regarding memory and learning. His disk and RAM metaphor is a useful way to think about the relationship between knowledge and sleep.
A metaphor can help understand the role of sleep and why alarm clocks are bad. We can compare the brain and its NREM-REM sleep cycles to an ordinary PC. During the day, while learning and experiencing new things, you store your new data in RAM memory. During the night, while first in NREM, you write the data down to the hard disk. During REM, which follows NREM in the night, you do the disk defragmentation, i.e. you organize data, sort them, build new connections, etc. Overnight, you repeat the write-and-defragment cycle until all RAM data is neatly written to the disk (for long-term use), and your RAM is clear and ready for a new day of learning. Upon waking up, you reboot the computer. If you reboot early with the use of an alarm clock, you often leave your disk fragmented. Your data access is slow, and your thinking is confused. Even worse, some of the data may not even get written to the disk. It is as if you have never stored it in RAM in the first place. In conclusion, if you use an alarm clock, you endanger your data.