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The cold wave that has brought sub-freezing temperatures to Kanto and other parts of Japan this week has no doubt led many to save on heating bills by retiring early and snuggling under their "denki mofu" (electric blanket).
But now Nikkan Gendai (Feb 4) has thrown a wet blanket on the notion that warm-as-toast bedding is a sensible way to hibernate. It says that humans, due to fewer hours of daylight during the winter months, naturally tend to sleep up to two more hours per night than they do in the summer. But should they have trouble sleeping at night, their biorhythm will become disordered, resulting in dysfunctional sleep that may even extend to the other months of the year.
Yohei Sugawara, an occupational therapist and author, advises readers how to improve their sleep. Essentially, he says, the greater the temperature that one's internal organs drops, the sleepier one will become, and the deeper one will sleep. In other words, once you fall asleep, if the internal body temperature continues to drop, and then the temperature starts rising in synch with the time to wake up, you will arise feeling well rested and invigorated.
"In order to reduce the internal body temperature, it's important to perspire and radiate heat," says Sugawara. "If bedding like an electric blanket that continually warms the entire body is used, then even if the body perspires, it becomes harder for the sweat to evaporate, and the body can't radiate heat. And because the internal body temperature doesn't drop, sleep tends to be lighter.
"Ordinarily a typical futon absorbs sweat during sleep, making it easier to radiate heat," Sugawara continues. "But electric blankets give priority to their mechanical heating function and are inferior in terms of ability to absorb sweat. Even if the blanket is only used to warm up the bedding when the sleeper first crawls into bed, it makes it more difficult for the internal body temperature to drop."
"In winter, activities by humans decline and their muscular power also diminishes," Sugawara adds. "Since the back muscles used to turn over in bed also weaken, the number of times we turn over during sleep also declines. But without turning over, air cannot be circulated between the futon and the body, making it impossible to radiate heat, and effective regulation of body heat ceases. To deal with this, people may keep the heat on in their bedrooms or put on heavier sleepwear, which makes it even more difficult for the internal body temperature to fall."
The most effective way to sleep in the winter is to devise ways to give priority to the parasympathetic nervous system, which functions when relaxing before bedtime. But in winter it becomes easier for the sympathetic nervous system to become active, and is difficult to reduce its operation before bedtime, making it harder to fall asleep.
To support the parasympathetic nerve function, Sugawara advises application of heat directly to the "senkotsu" (sacrum), a triangular shaped bone located at the bottom of the spine, just above the buttocks, where such nerves are clustered.
"First try holding a hot water bottle or thermal pack against the sacrum and then when you get into bed move the heat source to your feet," he suggests. "If you warm your ankles, the bottoms of your feet will radiate heat, causing the internal body temperature to drop, which should realize even better results."
Another suggestion is to set the timer on the heater to start warming up the room one hour before getting out of bed, so that the internal body temperature will gradually start to rise, thereby facilitating a natural process of awakening.
© Japan Today
29 Comments
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Tessa
I go to bed with "kairo" heating pads attached to the soles of my bedsocks. Never use a heater, and sleep like a baby!
Graham DeShazo
Scotch and a warm partner.....
GalapagosnoGairaishu
Since tomorrow is Saturday, I'm going to try turning off the blanket and see if this actually works. I don't have to go into the office, so I can always make up for any lost sleep, if it comes to that.
spahnmatthew
The occupational therapist raised some interesting insights. One note of caution though: beware of applying direct heat to the sacrum, for if that heat source shifts to your lower back during the night, the resulting inflammation of the lower back muscles will cause major stiffness. That happened to me.
A cool room definitely helps a person sleep. Also, books help too. Avoid television or other electronic screens.
Two months ago, I purchased a Philips wake-up clock that simulates the sunrise -- it was expensive, but worth it, especially during cold northeast USA winters.
Ranger_Miffy2
Finally bought an electric blanket after reading advice from a JT reader on laying it between the mattress and bottom sheet. Have slept incredibly comfortably for the first time in winter. Setting is kept very low (1-2). No more cold spots during the night. The cat loves it, too. Plus, have an oil-heater preset to warm the main room before I get up. Have never needed two more hours of sleep in winter. This article seems off the wall.
Warm blanket, cat, and snow falling. Winter delights.
papigiulio
We have a non electric blanket at home, I have no idea what material or what brand it is but I can honestly recommend this thin blanket. Once you wrap yourself into it, it works like a heater. If I find the brand and type I will post it here.
paulinusa
Years ago when electric blankets were the rage there was some concern about long term exposure to electromagnetic fields. Whether the science was valid or if today's blankets are safer I don't know.
papigiulio
Hmmm just checked for the label. there is none. All I know is that we bought it at costco. Just checked and I assume it is this one:
http://www.costco.com/microfiber-blankets.html
wanderlust
A couple of cats are also great for warming your feet and back...just watch out for their claws in the morning!
DaveAllTogether
I use an electric blanket to heat the bed. The blanket is turned off before I get in.
recherche88
I bought an electric foot warmer for my cats (for their whole bodies, not their paws), but they weren't interested. Now I put it in the foot of my bed where it performs its intended function. The cats still prefer to lie on my chest ; (
GW
Yeah forget electric blankets I have to do battle each night with 3cats & a dog, some nights are pretty rough & tumble so in theory I should look like a body builder but alas I just wake up every day wishing I could sleep another 11-2hrs haha!
nath
Yeah, Ranger, I love my electric blanket, too. I keep it set quite low, and I only use it on the lower part of my bed, because my feet get cold :( I would recommend electric blankets to anyone, so long as they remember to turn them off in the morning… because I think I forgot… again...
Carcharodon
Sorry, but almost no sleep expert will agree with this, reading in bed before sleep is a bad idea, Reading stimulates your brain, not relaxes it. If you have trouble sleeping you must eliminate all distractions, no cellphones, tablets, books in bed. Make your room as dark as possible and train yourself to realize that hitting the pillow is total shutdown time. Tea - herbal tea use, regular tea no, its a stimulant: caffeine. Some biohackers have found that a teaspoon of honey before bed has greatly improved their sleep. Others have found adding a resistant starch to their diet has greatly improved sleep quality, potato starch dissolved in water before bed.
As for electric blankets, haven't used on since I was a kid and then only to warm up the bed. Sleeping on an active one and so close to a EMF all night long? no thanks.
Kasper123
But how about them in Hokkaido, wheres it freazing cold in the winter?;)
TrevorPeace1
There's a simpler solution, from this bad sleeper's perspective - take a hot bath, drink some decent tea and snuggle with your better half. If you're single, stick with the hot bath and tea, and read a good book until you drop off.
And instead of an electric blanket, go with a decent down duvet and only a sheet between you and it.
subyyaki
Interesting advice. I just bought a programmable thermostat for our bedroom and hooked it up yesterday. Think I'll try some of these theories out!
SwissToni
Sounds like Hoo Doo to me. My understanding is that humans maintain a steady body temperature unless something has gone wrong. Warming your bed is all about keeping your extremities warm. This seems like an attempt to sell a book.
jpntdytmrow
wanderlustFeb. 07, 2014 - 12:14PM JST "A couple of cats are also great for warming your feet and back...just watch out for their claws in the morning!"
I fully agree. We each have a cat in addition to the fluffy socks, neck warmer, stocking cap and various layers, or those thick padded quilt jackets "hanten". That can eliminate the need for the heavy blankets during the night. this all after taking the recommended hot bath.
Not sure if it works, but my grandfather said that in in the war, he used newspapers under the blankets. Cardboard or other things stuffed in the windows helps on snowy or subzero nights. On one glass door, we actually hang a wool blanket.
Love Japanese insulation! But, it has made me realized how to live without central heating.
TakahiroDomingo
to generalize and apply rules in this matter is a bit stupid. tolerance to temperature extremes (cold and hot) vary tremendously from human to human. so, just do "whatever gets you through the night" and don't listen to these "authorities on warm blankets"
dracpoo2
Mine helps me.....also helps me keep my bill down
Ah_so
A hot bath before sleep in the worst thing to do - your body needs to cool down. We all associate warmth with sleep, but as the article above makes clear, it is quite the reverse.
Warming up a futon with an electric blanket about 30m before bed, and then switching it off, is a fraction of the cost of boiling the water for a hot water bottle.
Good if it works for you, but I could not manage it. Most experts on sleep recommend that a room be cooler than that - we are after all designed to sleep at night, when it is coooler.
thehedonist
Sleeping with the heat on / electric blanket is a waste. Wear heat tech long johns under your pajamas, pile blankets on your futon and use a " 湯たんぽ " (hot water bottle).
albaleo
"regular tea no, its a stimulant"
It's also a muscle relaxant, and can be effective in relaxing the body. Ask any Japanese mother whose baby won't calm down.
Bear27840
I do not use blankets or any type of clothing for at night I turn in to a furnace waking up having to use a towel to wipe the sweat off.
Try this some time especially with your truest love, of course there might not be much sleep so it is best to use this method on week's end.
Marilita Fabie-Fujisawa
We sleep with the heater on, 20 degrees...comfy!
Knox Harrington
Who the hell uses electric blankets? Thought they disappeared some time in the 70's.