Sleep: we need it and we still don’t know why

We spend one-third of our lives asleep, but we still don’t know why. New research is shining light on one of science’s enduring questions.
By Peter Meredith December 9, 2014 Reading Time: 8 Minutes

FOR FIVE YEARS, insomnia gnawed away at Kim Budimir’s life. Locked into a vicious cycle of fractured nights and exhausted days, the 36-year-old Adelaide resident would doze off in front of the TV in the evening and then, having crawled into bed, sleep until 2 or 3am.

“I wouldn’t be able to go back to sleep after that, so I’d get up and watch television,” Kim says. “By the time I needed to get ready for work, at about 6.30am, I was tired and ready to sleep. But that was impossible; I just had to push through it.”

At her desk after fewer than six hours of straight sleep, her brain fogged by fatigue and her stress levels amplified by anxiety over her chronic sleep deficit, Kim had to focus hard on avoiding mistakes in her demanding job at the office of the Premier of South Australia. She’d schedule challenging tasks in the morning and more mundane ones in the afternoon.

“After 2pm I was a basket case,” she says. “I had no social life…no desire to do anything but come home and sleep.”

By late 2011 Kim had had enough. With a referral from her GP, she contacted the Adelaide Institute for Sleep Health, based at the Repatriation General Hospital, and turned up for her first appointment early this year.

The sleep-wake cycle

KIM IS AMONG the 1.5 million Australians who’ve been tormented by one of 70 or so recognised sleep disorders. Whatever their form, these disorders have the same single outcome: sleep deprivation.

Sleep is a period of deep rest when humans and many animals are unaware of what’s happening around them. At various points during this state, voluntary muscles are paralysed, breathing and heartbeat slow down – and at times speed up – body temperature falls, and some parts of the brain become less active and others supercharged.

Most living creatures need this downtime every day. If they don’t get it, they experience mental and physical disturbances. But sleep is easily disrupted. We wake instantly at a loud noise, a flash of light or if shaken.

Two primary mechanisms power the sleep–wake cycle. One is ‘sleep pressure’, the simple need for slumber. The longer we’re awake, the greater the pressure. The other mechanism is the biological clock: the brain’s pacemaker. This remarkable machine resides in two pinhead-sized clumps of nerve cells known collectively as the suprachiasmatic nucleus (SCN). Sitting directly above the optic nerves, the SCN monitors the amount of light entering the eyes.  Once it has this information, it resets the clock every day, establishing the body’s circadian rhythm.

One of the crucial connections the SCN has in the brain is with the pineal gland, a pea-sized organ that releases melatonin, the sleep hormone (dubbed the hormone of darkness), as daylight fades. The SCN ensures melatonin levels rise during the night and fall towards dawn. It’s one of the major drivers of the sleep–wake cycle. If all is well with the system, this cycle is finely coordinated with the planet’s day–night timetable.

The importance of sleep

NOBODY REALLY KNOWS why we sleep, although theories include: sleep revitalises the brain and nervous system, builds protein and restores the brain’s control over muscles and other body systems. Dreaming may help consolidate memory and aid mental activities such as learning and reasoning.

“There is good evidence that sleep acts like a glue that holds memories together – that it’s important for memory consolidation, and the flip side, forgetting,” says Associate Professor Kurt Lushington, director of the Centre for Sleep Research at the University of South Australia. “You need to wipe some stuff out and reinforce other stuff.” Sleep also improves daytime concentration and alertness, he says.

“When someone’s alert they can think sideways, react differently, creatively, and process multiple things at a time, while their thinking and emotions are well coordinated and interacting.”

How much sleep needed varies from person to person and depends on many factors, including genetics. We sleep less as we age: four-year-olds require 10–14 hours, but most adults only 7–9 hours. Some adults seem naturally able to function well on less than seven. Other people need more than nine. People who sleep for eight hours a night in their 30s might need an hour less in their 60s.

If we don’t get enough, we struggle to concentrate, especially on dull, repetitive tasks. We react more slowly and we make mistakes, though we do better on more stimulating tasks. We’re also easily distracted, moody, irritable and even irrational. Worse, we may be so fatigued during the day that we doze off, maybe while doing something like driving. Extreme sleep deprivation is so unpleasant, it’s used as a form of torture.

Professor Drew Dawson, director of the Appleton Institute for Behavioural Science (an Adelaide-based campus of Central Queensland University), has long had an interest in the impacts of shiftwork on sleep. In 1997 he published a paper that likened the effects of fatigue to those of alcohol intoxication, expressing hours awake in terms of blood-alcohol concentration. Drew says a person who’s been awake for 24 hours continuously has a blood-alcohol equivalent of up to 0.1.

“So somebody driving home after their first night shift is as impaired as if they’ve had twice the legal limit of alcohol,” he says.

Different sleeping patterns during the ancient times

WE THINK of a normal night’s sleep as a single eight-hour stretch. Scientists call this monophasic sleep. But this hasn’t always been the norm.

In pre-industrial Europe, going back to Roman and ancient Greek times, biphasic sleep was common. People slept in two spells, separated around midnight by 1–2 hours of chatting, snacking, housework or sex. A few people still sleep like this. Premodern peoples such as ancient hunter-gatherer societies – and similar groups surviving today – had even less-structured sleep habits, termed polyphasic sleep.

They may have slept in groups, with individuals of different ages waking at different times through the night, ensuring that there was always someone alert to danger. They also took naps during the day, a bit like today’s so-called siesta cultures, in which people sleep for 5–6 hours at night and nap for 1–2 hours after lunch.

In the late 1800s, artificial light doomed both biphasic and polyphasic sleep. People carried on their daytime activities late into the night – and even right through it. Sleep was taken in a single, mostly uninterrupted stint and became compressed. As a result, many sleep experts believe we’re probably getting 1.5 hours less sleep than people did 100 years ago.

Sleeping disorders

LIFESTYLE-BASED sleep problems are just a few of the sleep disorders that bedevil our society. These disorders range from snoring and mild insomnia, sleep apnoea and narcolepsy, to restless leg syndrome and chronic insomnia. A 2012 report says that, combined, these disorders bleed the Australian economy of $36.4 billion annually. Although not all stem from circadian rhythm disturbances, they spawn the single overarching monster: sleep deprivation.

In a study published in April this year by the Appleton Institute, almost 40 per cent of people quizzed said they had fallen asleep at work or during meetings. Thirty per cent had called in sick because of sleep-related issues.

Sleep disorders are behind 9 per cent of work-related injuries, 8.3 per cent of depression and 7.6 per cent of non-work related road accidents. Some 90 per cent of Australians experience a sleep disorder at some point in their lives.

The big daddy of them all is obstructive sleep apnoea, which accounts for about half of all sleep disorders and has the biggest economic impact. Insomnia comes second, at about 30 per cent. Insomnia takes several forms. Mostly it’s transient, but when it persists, its impact on the sufferer’s life can be pervasive and distressing.

Professor Leon Lack, of Flinders University, Adelaide, is a sleep expert renowned internationally for his pioneering work on insomnia. He and co-researcher Dr Helen Wright have been studying the human circadian rhythm for more than 20 years.

“The main theme of our research is the involvement of circadian rhythms in insomnia, in people whose rhythms are delayed and who have trouble falling asleep and are waking late, and people whose rhythms are advanced and are falling asleep and waking too early and aren’t getting enough sleep,” Leon says.

Worry usually worsens the distress, creating a nasty feedback loop. You don’t sleep. You worry about not sleeping. Your worry keeps you awake more. “The anxiety night after night is probably the biggest issue,” Leon says.

Some people’s body clocks run either abnormally fast or slow. In less extreme forms, this mistiming turns some people either into owls (late-nighters) or larks (early risers). It doesn’t take much to push the body clock just a little further either way and turn owls and larks into insomniacs. Sometimes the trigger is stress, caused by an event such as a marriage break-up (as was the case with Kim Budimir) or a death in the family. With luck the stress passes and the insomnia wanes. But sometimes the insomnia becomes entrenched.

Teenagers are notorious sufferers of phase-delayed insomnia. Mostly this is triggered by the momentous changes taking place in their brains and bodies during adolescence, but it’s exacerbated by poor sleep habits like watching TV or using laptops, tablets and mobile phones in bed late into the night.

Leon and Helen have pioneered treatments for circadian rhythm mistiming using bright light. They’ve found that light at the right intensity and colour (blue, green or blue-green are best) administered at strategic points in the rhythm can suppress melatonin production and push the rhythm in one direction or another.

Bright light in the early part of the night delays the rhythm, so that a person wants to go to sleep later, while bright light in the early morning advances it, so that the sleeper wakes earlier.

Although intense interior light may be enough to shift the rhythm in milder cases, more powerful light sources could be needed in others. Initially, the researchers used light boxes as a source, but they were cumbersome and patients didn’t enjoy sitting in front of them for long. Then, in 1997, Leon had a brainwave. Opening his garden shed one day, he saw that his daughter had left the lights of her bicycle on.

“The LEDs were still flashing after three days. I realised immediately they were a very efficient source of very bright light. It occurred to me that they might enable you to put the light source close to the eyes to be effective for light therapy, but with much less electrical power needed compared with the conventional light boxes.”

So was born the concept of light-emitting spectacles that insomniacs (and even people suffering from jet lag) could wear for their treatment with minimal inconvenience. Helen worked on prototypes for her PhD and now the latest design, Retimer, with LEDs and rechargeable batteries in the frame, is about to come on to the market.

Both Leon and Helen take time out from their research to treat patients at a couple of sleep clinics, Leon at the Adelaide Institute for Sleep Health. And it was here that he and Kim Budimir met in January this year.

Treatment for the insomniac

FROM THE START Kim was sceptical. “I’d tried everything and nothing had worked,” she says. “When Professor Lack told me we were going to sit and talk and then make some minor adjustments to my day, I couldn’t see how this was going to help.”

First Leon asked Kim to go to bed later. “He wanted me to stay up till 10.30. For someone who was in bed by nine and awake at three or four, that hurt. I almost cried!”

Kim realised the aim was to begin the gradual process of pushing her circadian rhythm back to its normal timeslot.

“That lasted 2–4 weeks. Then he added that nugget: ‘Let’s turn on every light in every room you’re in.’’’

Accustomed to unwinding in soft, cosy light in the evenings, Kim now had to do everything under a harsh glare. It was a shock to her system – but it worked spectacularly. Within weeks she was falling asleep at about 11pm and waking at 6am, getting about seven hours sleep a night. She had the last of six consultations with Leon in May.

“These past few months have brought a huge change to how I feel,” she says. “I feel good in the morning and during the day, just naturally tired from my work and not exhausted by fatigue from lack of sleep.

“I’m amazed that a couple of quite simple tweaks to behaviour have resulted in completely shifting my sleep pattern and making it more normal.”

 

The full story can be found in Australian Geographic #110.