Sleeping-goods manufacturer Nishikawa Sangyo Co. Ltd., founded in Omi Province (modern-day Shiga Prefecture) in 1566, got its start in business selling mosquito netting. The company’s Tokyo retail outlet, on the opposite side of the Nihonbashi Bridge from the Mitsukoshi department store, has been in operation since 1615.

Not content to, er, rest on its laurels, the 446-year-old company established the Japan Research Laboratory of Sleep Science in November 1984, marking a first for the bedding industry to involve itself directly in the efficacy of sleep.

“Bedding is not only a furnishing for sleep, but a thing that helps consumers feel rested and comfortable the next day,” its president, Yasuyuki Nishikawa, is quoted as saying in the July issue of Japan Close-Up, an English-language magazine published by the PHP Institute in Kyoto.

Reflecting the findings from its laboratory, Nishikawa’s Nihonbashi shop this summer has been featuring the Cool Touch line of sheets, pillowcases and mattress pads designed to dispel heat, and should be particularly welcome on so-called tropical nights, when the mercury hovers above 25 degrees Celsius.

But the best scientific efforts by the bedding industry notwithstanding, large numbers of Japanese are not getting sufficient rest. Business magazine Shukan Diamond devotes a whopping 58 pages of its July 28 issue to insomnia, anxiety and fatigue. According to a survey conducted in 2000, more than one Japanese in five, or 21.4 percent, suffer from sleep disorders, which may include difficulties in falling asleep or staying asleep, waking up too early and insufficient sleep duration.

Research findings suggest people with chronic sleep problems run a 2.1- to 3.0-fold higher risk of developing some form of depression and correlations have also been found between insomnia and risk of developing lifestyle-related diseases such as hypertension or diabetes.

Shukan Diamond introduces a two-page spread of some of the more exotic sleep-related products on the market. These include a special LED bedroom ceiling light from Sharp that casts a pinkish hue from one hour before bedtime to elicit drowsiness.

More efforts are being devoted to understanding kakure fumin (hidden or crypto-insomnia), a common condition whose causes are more complicated than simple lack of sufficient sleep. Its most recognizable symptom is the persistent feeling upon awakening of not having sufficiently rested. Some sufferers of crypto-insomnia are likely to graduate to full-blown insomnia.

Sleep disorders may have one new physiological cause that no one has anticipated. Aera (Aug. 6) takes a look at so-called bed mobilers. It seems that when goo Research surveyed 1,818 smartphone users between the ages of 20 and 60, it found that about 40 percent of them spend 20 minutes or longer texting and perusing social network sites while in bed.

Can such activities be a bad thing? Possibly, as it seems the liquid crystal displays of personal computers and smartphones emit blue light at wavelengths of 400 — 500 nanometers. “Blue light waves emit high energy, which is not absorbed by the cornea or lens but is transmitted to the retina,” says Kazuo Tsubota, a professor of Ophthalmology at Keio University’s Faculty of Medicine. “They may also aggravate eye fatigue and damage the retina.”

The blue light emanating from smartphones and other high-tech toys appears to inhibit the body’s production of melatonin, a hormone that regulates the sleep-wake cycle. In preliminary experiments at Obirin University’s Faculty of Medicine conducted over a two-week period, two test groups used a smartphone for one hour before bedtime. The first wore special eyeglasses designed to filter out blue light. Those in the group who did not wear the eyeglasses awakened from sleep more easily and tended to sleep for shorter periods.

“Full-fledged research comes next, but we see a strong likelihood that blue light affects the rhythm of sleep,” says Obirin professor Yoishihiko Koga. “Smartphones may be a major factor in the ‘crypto-insomnia’ that’s one step short of full-blown insomnia.”

Tabloid newspaper Nikkan Gendai (July 11) introduces Dr. Satoru Tsubota (no relation to Kazuo, above), assistant director of a clinic in Toyama Prefecture and author of the recently published self-help book “No mo Karada mo Saewataru Ippun Kamin-ho” (“The One-Minute Nap Method That Chills Out Both the Brain and the Body,” Subarusha, ¥1,365).

“The trick to the one-minute nap is to do it before you feel sleepy,” says Tsubota, who explains that so doing will prevent the napper from falling into a deep sleep. Tsubota recommends sitting in a chair at the office for the one-minute session while feigning to be thinking about something. A good time to do it is just before the start of a business meeting.

A certain Mr. A, age 38, whose sleep has been repeatedly interrupted since the recent birth of his first child, was dubious about the one-minute nap method until he tried it. He found not only was he able to avoid slip-ups on the job but felt less grumpy as well. For those who suffer from sleep apnea or other physiological disorders on the other hand, Nikkan Gendai advises that a sleep specialist be consulted.

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