Past their bedtime
From the cradle to the rest home, sleep of full cycles is vital.
Adolescents undergo hormone changes and a shift in their circadian rhythm, from the early sleep of a child to a bedtime past their parents’. Modern life and particularly early school times are denying their biological clocks as well as robbing them of early-morning, REM-heavy sleep. Data shows that early school starts are bad for teenagers’ health, academic performance, and even mortality figures.
One of Massey University sleep researcher Philippa Gander’s students did research a few years ago on changes in sleep time associated with hormonal changes at Wellington High School. She found Year 9 students suffer some social jetlag but Year 12s were much worse – so the senior school made the first period of the day a study period. Results improved.
The connection between poor health and poorer sleep quality is often not made or mentioned to GPs.
Although the picture is now complicated by more devices in the bedroom, Gander says, “what it looked like was that later start for the senior school had protected the kids from the adverse effects of their technology”.
It’s a myth that older adults need less sleep, says University of California professor of neuroscience and psychology Matthew Walker.
Although REM sleep remains largely stable in midlife, the deep-NREM sleep that stabilises after adolescence begins to decline, due to changes in parts of the brain as we age. The deep NREM brainwaves become smaller, fewer, and less powerful. The circadian rhythm and melatonin release become weaker.
Older people also frequently suffer fragmentation of their sleep, including from medications, physical ailments and ills such as depression, and a weaker bladder. Sleep doesn’t refresh as it did when people were teenagers.
Poorer sleep efficiency, as it’s known, is associated with higher mortality risk, worse physical and mental health, lower energy and more forgetfulness.
However, the connection between poor health and poorer sleep quality is often not made or mentioned to GPs.
What can be done? Walker has a few suggestions. In the bedroom, an easy-to-reach side lamp, a phone by the bed in case of emergencies, dim or motion-detecting night-lights, and removing obstacles en route to the bathroom.
Wear sunglasses during morning exercise to reduce light to your inner clock; wear sunscreen but not sunglasses in the afternoon outside to delay the release of melatonin; talk to your GP about taking melatonin in the evening. In older people, melatonin has been shown to improve circadian rhythms, improving sleep patterns and quality, and morning alertness, says Walker.
Alice Gregory, a professor of psychology at Goldsmiths, University of London, notes that women approaching or experiencing menopause often report poorer sleep duration and quality. Some studies suggest that hormone replacement therapy can improve sleep – but do talk to your GP.
Gregory also notes that the lenses of our eyes yellow as we age, and cataracts often develop, both cutting the amount of blue light that gets through. Gander says scheduling light treatment and exercise can help older people hold their body clock in a regular pattern and improve working functions.
mats, from nightcaps to giving up booze and coffee, to demanding melatonin or sleeping pills from their doctor. They will know that Billy Crystal (“I sleep like a baby: I’m up every two hours”), Michael Jackson, Vladimir Nabokov and Kim Cattrall are among those who have suffered chronic insomnia – that is, an inability to initiate or maintain sleep and an impaired waking function lasting for at least a month. Cattrall, who has tried cognitive behaviour therapy, had to pull out of a play in London due to the “gorilla sitting on my chest”.
Former British Prime Minister Margaret Thatcher said she needed only four hours’ sleep but later developed dementia. Incumbent Theresa May has spoken of how any senior government role cuts into shut-eye. When asked what he wanted for Christmas after months of campaigning to be President of the United States, Barack Obama said without hesitation, “Eight hours’ sleep”. Donald Trump thinks sleep is for wimps.
HOW SLEEP WORKS
Insomnia sufferers will not be surprised that the sleep-health industry, including pills, mattresses and now devices and apps, is worth an estimated US$40 billion and growing. What they may not know is how science has deepened our understanding of exactly how sleep works, and why we desperately need the recommended seven to nine hours of sleep each night.
Two main factors determine our sleep pat- terns. One is a “clock” in our brain called the suprachiasmatic nucleus which, aided by light from the sun, creates a roughly 24-hour cycle that makes us tired and alert at regular times of the day – our circadian rhythm. This clock, a group of about 20,000 neurons, regulates body temperature, our metabolic rate and the release of some hormones such as melatonin at night, which brings on sleep. The other factor is what’s called “sleep pressure”. It’s caused by a chemical called adenosine that builds up in the brain throughout the day, making us feel ever more sleepy. Adenosine levels peak after 12-16 hours of people being awake. We can “mute the signal” of adenosine using caffeine, which competes with adenosine for receptors in the brain.
Sleep degrades and removes the adenosine, so naps reduce sleep pressure and eight hours will clear it out. The two systems, the circadian wake drive and the sleep drive, actually work independently, though they are usually aligned. So if you work an all-nighter, you’ll feel more awake at some hours than others.
So what happens when we sleep? Adults sleep in 90-minute cycles, beginning in what’s called non-REM, or NREM, sleep. REM is rapid eye movement, the flickering back and forth under the eyelids that you can see when people are asleep, closely associated with dreaming and accompanied – we know now – by active brainwaves, similar to those we have when we are awake. But first, we enter non-REM sleep, when the eyes and brainwaves are calm. Non-REM sleep has four stages, and as the 90 minutes tick by, we descend into deeper slumber. In
Sleep enriches our ability to learn, memorise and make logical decisions. It helps us fight infection and maintain our metabolism.
NREM stages three and four we enjoy long, slow-wave sleep. REM sleep comes next, and then the cycle begins again.
To restore the brain’s capacity for learning, to retain new memories and make new connections, and to be fully refreshed, we need both non-REM and REM sleep. Memory refreshment, Berkeley’s Matthew Walker found in one study, was closely related to lighter, stage-two NREM sleep, and what are called sleep spindles – short and powerful bursts of electrical activity in the brain. The more sleep spindles, the better the ability to learn was replenished, the study found.
The eight-hour sleep cycle is not symmetrical, however. REM sleep increases in proportion as we head towards morning, as deep NREM sleep decreases. This pattern appears to help the brain find the ideal balance between keeping what’s old but useful and leaving sufficient room for the new.
NREM sleep helps transfer and consolidate newly learned information into long-term memory and weeds out unnecessary neural connections, says Walker, while dreaming REM sleep strengthens those connections. This consolidation and match-up with your existing back catalogue of memories also fuels creativity. Novel links and vast associative networks are created, giving you insights and overarching understanding. NREM sleep, particularly that in the latemorning cycle, which is packed with spindles, also helps cement motor skills, such as riding a bike or playing the piano.
Our emotional intelligence depends on getting our quota of REM sleep. It finetunes the emotional circuits of the brain, enabling us to negotiate the daily thicket of expressions, gestures and behaviour, guiding our decision-making and regulating our feelings. This means those early starts to get ahead at work or make it to the gym could be taking a serious toll. REM sleep, argues Walker, a bright-eyed and fit 40-something who gives himself a non-negotiable eighthour “sleep opportunity” each night, made humans king of the beasts, by boosting our cognitive intelligence and sociocultural complexity.
WHAT’S RUINING OUR SLEEP?
A hundred years ago, less than 2% of the US population slept six hours or less a night, Walker says. Now, almost 30% do. More than 65% of the US population don’t get the recommended 7-9 hours of nightly sleep through the week. It’s much the same across the developed world. What’s to blame? One of the biggest factors is artificial lighting, especially the explosion of LEDs, and digital screens, which are rich in blue light. The circadian clock receives light information exclusively from a special type of neuron in the eye, which is predominantly influenced by blue light at high intensities. Exposure to blue wavelengths in the evening, including from domestic lighting and screens, delays the clock, making it harder to fall asleep and wake in the morning and impeding our attention. Exposure to blue light from the sky is greatest around midday, says a study on the impacts of blue light on health and the environment published by the Royal Society of NZ Te Apārangi in November.
What can we do? We need darkness to release melatonin. Dim half of the lights at night, Walker says, and limit your time in front of devices and the TV. The converse is to get plenty of light during the day, particularly in the morning and early afternoon. You can also choose lights with warmer colours or even buy yellow-tinted glasses that restrict blue light reaching your eyes.
Sleeping pills: Do sleeping pills help or hinder our sleep? Sleeping pills give people a form of sleep, says Gander, but it’s not like getting an understanding of people’s sleep processes. They are a particular problem for older people, she says, who tend to be taking other drugs as well. Walker notes that they are sedatives, whether the older benzodiazepines or the newer drugs, which are slightly less heavy in their effects. They stop the brain cells from firing, like alcohol. If you compare natural sleeping brainwave activity with that under the newer drugs, the largest, deepest brainwaves are missing, he says. And they can make you groggy, forgetful and more prone to mistakes the next day, fuelling extra caffeine requirements and hence a desire for more pills. People can get addicted to them, and going off them can cause “rebound insomnia”, Walker says, frequently worse than the original.
Yet Zopiclone, just one of the insomnia treatments available, was the 14th-highestvolume medicine dispensed in New Zealand in 2013-14, according to GP advisory group BPAC NZ, with about 120 prescriptions being dispensed per 1000 registered patients initially.
Do they help? A recent meta-analysis by leading researchers of published studies found only “slight improvements” over placebos in the time it took to fall asleep, says Walker. Some studies suggest sleeping pills may actually weaken memory connections normally made during sleep. Even worse: “Sleeping pills are associated with
Sleep before a game helps us perform better but also helps us recover faster after we’ve done the hard work. REM sleep made humans king of the beasts, by boosting our cognitive intelligence and sociocultural complexity.
a significantly higher rate of death as well as cancer,” says Walker. The American College of Physicians recommends CBT-I rather than sleeping pills.
Alcohol: Many people believe that a glass or two at night helps them sleep. It doesn’t. We become relaxed because booze affects the prefrontal cortex area of our brain first, the impulse-control part. Eventually it begins to sedate other parts. “The electrical brainwave state you enter via alcohol is not that of natural sleep,” says Walker. “Rather, it is akin to a light form of anaesthesia.” More than that, alcohol fragments our night’s slumber, waking us up for brief periods and so not letting sleep do its restorative magic. We often don’t remember waking, so fail to make the connection with being exhausted the next day. “Second, alcohol is one of the most powerful suppressors of REM sleep that we know of.” Byproduct chemicals called aldehydes that the body produces when metabolising alcohol block the brain’s ability to generate REM sleep. And it makes us urinate more.
Caffeine: Found in energy drinks, tea and dark chocolate as well as in coffee, caffeine interferes with the sleep pressure of adenosine in our brains to make us more alert. It has a half-life of six hours, Walker told the Listener, but there’s still a quarter of it washing around your system 12 hours later. Stop drinking coffee after about 10am, he recommends.
THE FUTURE OF SLEEP
Technology, the nemesis of sleep, would like to make amends. Many programs now have night-mode options, and a number of apps like f.lux or Twilight reduce blue-light content.
Smart watches, and apps such as Sleep Cycle, Calm, Sleep As Android, Pzizz, White Noise and Pillow, either track and evaluate your sleep cycles by monitoring sounds and movement and promise to wake you at the optimal time, or they play relaxing sounds or white noise, help you meditate or read you stories. But experts such as Alice Gregory, a professor of psychology at Goldsmiths, University of London, argue that sleep should be natural, and focusing on it too much through such monitoring can cause its own problems.
Walker says there has been research to give people’s brains small electrical pulses to stimulate deep-sleep brainwaves and sleep spindles, or play them quiet auditory tones, and the early results have been promising.
If you compare natural sleeping brainwave activity to that under the newer sleeping pills, the largest, deepest brainwaves are missing.
On the driving-safety front, recent studies suggest it might be possible to have a blood or urine test for sleep-deprivation based on metabolites. Such a tool would be useful for police to get dangerously tired drivers off the road, or perhaps in the near future your car would, like alcohol readers, refuse to let you drive if you hadn’t had sufficient sleep.
Gregory says although we can help ourselves in many ways, such as spending less time in front of Netflix, employers can help, too. She notes initiatives such as companies paying staff bonuses to encourage more shut eye, setting up “nap pods” at work, allowing flexible work hours to respect individual differences in sleep-timing preferences and encouraging working from home to reduce time spent commuting.
The answer’s simple, even if the question’s become more difficult. It’s getting enough sleep, of good quality, and getting it at the right time, says Massey University’s Gander. “You can’t compromise sleep without compromising your waking health.”