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Waking up to the mechanics of sleep

by Rowan Hooper

Special To The Japan Times

Feeling tired? Wish you had more time in your life? Got too much to do? I answer all three questions in the affirmative, and I am far from alone — in fact, almost everyone I know feels the same. The problem may be a lack of sleep, and, counterintuitively, it may also be a lack of play. But let’s start with the former.

We would like more sleep, but we typically feel as if we just don’t have the time. The problem is particularly acute in Japan. The Ministry of Health, Labor and Welfare tracks the number of people who report sleeping less than six hours in a 24-hour cycle, and the figure has been steadily increasing over the years. In 2007, around 28 percent of people were getting less than six hours per cycle; by 2015, the figure had climbed to 40 percent. Given that physicians recommend people get between seven and eight hours sleep per night, this is clearly a problem.

It’s tempting to see Japan’s problems with sleep — or perhaps it’s better to say Japan’s motivation to work — in the light of the anxiety sowed by Buddha. He was not enamored of sleep and warned his followers not to spend too long in bed, proclaiming: “When one is lazy, gluttonous, snoozing and lolling on the bed like a great fat pig, he will be reborn again and again.”

According to a report by research group RAND Corp., the economic cost of sleep deprivation is $50 billion in the United Kingdom, amounting to 1.9 percent of gross domestic product. The corresponding figure in Japan is $138 billion, or some 2.9 percent of GDP. That’s an extraordinary figure — in short, trying to squeeze too much out of each day is sapping our economic as well as our physical strength.

Researchers worldwide are devoting plenty of resources into the study of sleep. We basically know that we need sleep to feel rested. We also know that REM sleep in particular, the phase of sleep where brain waves are short and during which we have the most dreams, is where we consolidate information picked up during the day into long-term memories. However, we don’t know much about the details. The fundamental reasons for sleep and the mechanisms that regulate different phases of the activity are, for the most part, unknown.

This is where Hiroki Ueda and his research group at the University of Tokyo’s Graduate School of Medicine and the Riken Quantitative Biology Center, come in. Professor Ueda uses mice in his research, but is primarily interested in human sleep and, more broadly speaking, human consciousness.

“Consciousness is hard to study because it is hard to measure,” Ueda says. “In most cases, however, it is tightly coupled with the waking state.”

In other words, we don’t know exactly what consciousness is, but we know that we can only perceive it when we are awake. By understanding sleep, therefore, we can understand the bigger question.

“Fortunately,” Ueda says, “the awake state and the sleeping state can also be objectively measured. I believe that sleep research will pave the way to a study of consciousness in the future.”

All animals sleep — even the simplest animals such as nematode worms and fruit flies have periods of sleep-like rest.

As far as humans are concerned, sleep duration changes over time. When we are newborn babies, we sleep for 20 hours a day. In old age, however, we may only need five hours. Sleep is a period of recovery; it gives the body an opportunity to remove waste products and recharge the immune system. It is also a period of consolidation, allowing the brain a chance to process what we’ve done that day and put it into memory stores.

To try and get a handle on the manner in which humans sleep and for how long, Ueda’s team built a theoretical model and used it to identify seven genes responsible for causing mice to stay awake or fall asleep. His team used a new form of gene editing called CRISPR to make genetically modified mice. He found that a mechanism regulated by calcium is responsible for controlling the length of sleep. In effect, he found that mice needed an influx of calcium in the neurons — the specialized cells of the brain — in order to fall asleep. Correspondingly, mice would also wake up if calcium was removed from neurons.

Some of the genetically modified mice slept less than regular mice. Some humans are able to sleep for shorter periods of time without apparent cost, but that’s not the case for mice. The genes that are linked in the mice to shorter sleep are also linked in people to schizophrenia, bipolar disorders, depression and autism if they are impaired, Ueda says.

“This research has provided us with a wide range of potential targets for future research and therapies,” Ueda says. “We have discovered the regulator of sleep duration. Many mental disorders and neurodegenerative diseases are also associated with sleep disorders, so understanding how sleep is regulated may lead to a deeper understanding of those diseases and future treatments.”

The Rand Corp. report on sleep says that increasing the amount of sleep from under six hours to between six and seven hours per day could boost Japan’s economy by $75.7 billion. This therefore seems to suggest that we would be more productive in the office if we work less hours. Now we just need to convince our bosses that this is the case.

Natural Selections covers issues related to scientific research in Japan on the fourth Saturday of the month. Rowan Hooper is the news editor of New Scientist magazine. Follow him on Twitter @rowhoop.