By Angus Dalton
Our weekly science newsletter, Examine, has been running a miniseries of deep dives on the evidence-based pillars of good health, including exercise, diet and stress. Sign up here to get Examine in your inbox each week for free.
It’s the forbidden fruit of the modern world, and one we taste all too often: the snooze button.
It wasn’t so long ago that we came to realise sleep has at least equal bearing to food and exercise when it comes to health, happiness and longevity. Good sleep cuts the risk of dementia, heart disease and poor mental health.
Good sleep cuts the risk of dementia, heart disease and poor mental health.Credit: Aresna Villanueva
But while much has been written about how to get a healthy night’s sleep, what about its eventual end – waking up?
Too often I wake up after a perfect eight-hour slumber as fresh as a corpse. Then I spend the first two hours of my day behaving like a reanimated one.
So what can we do to maximise morning pizazz? Is hitting the snooze button sabotaging our chances of feeling fresh?
The snooze button sweet-spot
When light hits your eyes or your alarm blares, a five-centimetre long, pencil-thin structure at the back of your brain called the reticular activating system (RAS) triggers the production of excitatory neurotransmitters and begins clearing out the sleepy chemicals from your brain.
We might feel groggy or “sleep drunk” for 20 to 30 minutes – and sometimes up to two hours – as these processes take place.
That’s why hitting the snooze button mightn’t be a bad thing.
Researchers have worried that snoozing could shorten sleep and fragment slumber because snoozers generally set their alarms earlier than those who spring straight out of bed, according to sleep scientist Tina Sundelin, an associate professor at Stockholm University.
But her research revealed that a snooze of 20 to 30 minutes may allow the brain more time to run its wake-up work.
Analysing the saliva of snoozers and people who get up straight away showed the snoozers had slightly higher levels of cortisol, which is associated with alertness, upon waking. Snoozers also performed better on cognitive tasks and had lost out on only about six minutes of sleep.
Sundelin’s study was relatively small, and more data is needed to confirm these effects, but other studies have found there’s at least no difference in sleepiness upon waking between snoozers and non-snoozers, busting the idea that delaying your wake-up is a bad thing.
But if you choose to snooze, there’s a sweet spot you shouldn’t miss.
There are four stages of sleep – two lighter stages and two phases of deeper slow-wave sleep (SWS).
If you wake up during deep sleep, you’re more likely to experience grogginess – “sleep inertia”. Hitting the snooze button for 20 to 30 minutes gives you a chance to wake up again during a lighter stage of sleep.
But snooze for more than 30 minutes and you risk falling back into a deep sleep stage and waking up feeling dazed and “overslept”.
Certain apps promise to track your sleep and trigger their alarm when you’re in a lighter stage, but many scientists are sceptical of their accuracy. One neuroscientist called them “fundamentally flawed”. You’re probably better off just setting your alarm at a regular time each day.
The three key factors for waking up
Once you’re up, what can you do to kill that groggy feeling faster? A Nature Communications study of 833 people by scientists at UC Berkeley identified three tweaks, beyond exposure to sunlight shortly after waking.
Good-quality carbs and a moderate amount of protein were associated with more energy in the morning.Credit: Getty Images
The first is obvious: sleeping later and longer helped people wake up fresh. But researchers also identified the perfect breakfast for an energised morning.
The worst breakfast for grogginess was a high-sugar option (sorry, lovers of Coco Pops). The best for accelerating morning energy was the high-carb option with a moderate amount of protein (say, scrambled eggs on slab of sourdough).
The last component was exercise – but not upon waking. The level of activity the previous day predicted how jazzed participants felt the next morning. So if you’re dragging yourself through a jog, walk or swim, you can think of it as helping earn yourself an energised morning the next day.
The study included twins, which helps scientists disentangle the role of genes. They found that genetics accounted for only about 25 per cent of how people felt upon waking.
“How you wake up each day is very much under your own control, based on how you structure your life and your sleep,” study author Professor Matthew Walker said. “You don’t need to feel resigned to any fate.”
The magic sleep number for longevity
Of course, the biggest thing you can do to wake up well is to sleep well. We know that involves slashing pre-bed screen time, dimming artificial light at night and ditching afternoon caffeine.
But it’s worth looking at a study that demonstrates just how damaging these modern sleep-stealers are to our health.
A chart comparing the sleep duration of humans to a range of other mammals. Our closest relatives – including chimps and baboons – sleep longer than us.Credit: Jerome M Siegel, The Lancet Neurology
We’ve long assumed that people sleep less in the modern world compared to pre-industrial times. Many non-human primates, our closest animal analogues, fall asleep at sunset for 10 to 12 hours and arise at dawn.
“Human beings might be expected to show this same pattern of dusk-to-dawn sleep,” writes evolutionary sleep scientist Professor Jerome Siegel in The Lancet Neurology. But he says a 2015 study into present-day hunter-gatherers living traditional lifestyles in Africa and South America refuted that idea.
Once night fell, the people in the study spent two to three hours cooking and chatting in the firelight. Then they slept for six to eight hours. That schedule is not dissimilar to their city counterparts.
However, free from the scourge of screens and artificial light, rates of insomnia in the hunter-gatherers were below 2 per cent, compared to 10-30 per cent in Australia and the UK.
The excellent sleep health of the hunter-gatherers may have contributed to very low rates of coronary artery disease and Alzheimer’s. It goes to show just how important wrangling artificial light and screen time is for city-slickers.
The magic number to aim for sits right in the middle of that six- to eight-hour average hit by the hunter-gatherers each night.
“Epidemiological studies in industrial societies, including as many as one million participants who were followed up for a maximum of six years, have consistently shown that seven hours of sleep predicts the longest lifespan,” Siegel writes.
Make the most of your health, relationships, fitness and nutrition with our Live Well newsletter. Get it in your inbox every Monday.