Many not sleeping enough – or well enough – and that's a killer

Tokyo -- Many of us are in the habit of burning the candle at both ends during the week and crashing on the weekend, but experts are issuing increasingly dire warnings about the dangers of "sleep deficit" -- a chronic shortage of rest that is wreaking havoc on our brains and bodies.

While Japan ranked dead last among 100 countries in hours slept, the U.S. Centers for Disease Control says one-third of Americans are not getting the recommended minimum of seven hours a night.

CBS News' Lucy Craft reports that in Japan, it has become socially acceptable to grab 40 winks just about anywhere, be it on a train, over coffee, even in parliament -- as Prime Minister Shinzo Abe himself has been caught doing on occasion. One expat, 

Snoozing in public is so common, it even has a name; "inemuri," or sleeping on duty. Jonathan William Mattice, who lived in Tokyo for years, has dedicated a Facebook page, "Nobody Sleeps Like The Japanese Do," to showcasing some of the more extreme examples.

But among a growing number of Japanese, the alarm has gone off about the wisdom of sacrificing sleep to work more.

Stanford University professor Seiji Nishino, who runs the school's Sleep and Circadian Neurobiology Lab, says chronic sleep deprivation afflicts Americans and Japanese alike. 

We're staying up "too late," he warns, "and that's not only for adults, also for the kids. Same tendency."

Worried about the impact of sleeplessness on productivity, a few Japanese companies are now encouraging employees to take power naps -- on the job. At least one firm pays its workers to get enough sleep at night, and Japanese cities now feature "napping cafes" for those who need a rest stop but can't get back to the comfort of their beds.

In the U.S., the CDC says our irregular, 24-7, constantly connected lifestyles put us at risk for obesity, cancer, dementia and a shortened lifespan, not to mention hampering job performance.  

Author of a comic book of sleep tips, Nishino advises CEOs and sumo wrestlers alike to slow down and unplug — well before hitting the hay.

He and other sleep researchers say, even if you get seven to eight hours, quantity does not always equal quality.

"Most people are concerned with length of sleep, but quality is also important," Nishino says. Quality shut-eye starts with a regular pre-sleep routine, like an evening stroll or reading a book, and most definitely not checking email one last time.

Sleep, Nishino warns, can be our best friend — or our worst enemy.