Need a good night's sleep? Try changing how you think about it

Our hectic modern lives can often leave us feeling sleep-deprived, but what if much of a good night's sleep was down to our state of mind?

How did you sleep last night? If you tossed and turned, or stared at the clock, it's likely you'll probably feel less-than-refreshed. But that groggy, tired feeling may not just be down to the quantity, or perhaps even the quality, of your sleep – it can also depend on your mindset. Because what you tell yourself the next day about how you slept, and about how much it matters, can make a difference to how you perceive your tiredness.

"Everybody knows the idea of sleep quality. They assume that it is based on people's sleep performance during the night, as something that you can measure," says Nicole Tang, director for the Warwick Sleep and Pain Lab at the University of Warwick in the UK. "But what happened afterwards, and what happened just before, could also have an influence."

Tang's own work in this area is part of a growing body of research that suggests sleeping through the night isn't the only key to feeling refreshed the next morning. Our perception of sleep, our mood when assessing how tired we are and what we are doing at that time can all make a difference, Tang and her colleagues say.

The idea that mindset directly affects our sleep isn't new. Decades of research has largely agreed that, in fact, psychological processes are likely the main driver behind insomnia: our sleep is disrupted when we're in an elevated state of psychological arousal, which often results from our thoughts, beliefs, and how we focus our attention.

Still, many of us would assume that, if we feel tired, it's because we slept poorly – tossing and turning all night, unable to fall into the kind of rejuvenating slumber we all hope for.

For decades, however, a phenomenon often called "paradoxical insomnia" has puzzled scientists. This is where people believe they had a poor night of sleep, feel fatigued – and yet when their sleep is objectively measured, such as with polysomnography, it is within the normal range. This state may be more common than people realise. Some research suggests it could apply to the majority of insomnia cases. One systematic review of studies identified the findings on prevalence among insomnia patients as ranging from 8% to 66%.

To be clear, insomnia, and its potential risks, are very real. And no one would argue that, if you consistently feel tired, you shouldn't make whatever tweaks to your sleep that you can. But the idea that how we view a bad night's sleep could change how tired we feel is an intriguing, and potentially empowering, consideration. At best? It means you might be able to feel more awake without having to clock up more hours of shut-eye.

This approach can conflict with what we're often told about sleep: namely, that consistently logging a certain number of hours, without wakes, is absolutely crucial to well-being, one of the main ideas driving a $78bn (£58bn), and growing, industry. In fact, experts say, the exact relationship between sleep duration and our long-term health remains unclear. The research tends to be mixed and even when a link is found, studies generally highlight associations between sleep and health, rather than causations. In other words, the lack of sleep could be the cause of the problem, or it could be down to an underlying issue that keeps someone from sleeping well – people with respiratory problems, for example, often suffer poorer sleep.

"We're problematising our sleep," says David Samson, an evolutionary anthropologist and director of the Sleep and Human Evolution Lab at the University of Toronto, as well as author of the forthcoming book The Sleepless Ape: The strange and unexpected story of how social sleep made us human. By using objective measures such as actigraphy, which monitors activity and rest cycles, he and other researchers have found that people from hunter-gather societies typically get between 5.7 and 7.1 hours of sleep per night – on the lower end of the scale compared to industrial societies. Their sleep is also more fragmented.

But it also doesn't bother them, says Samson. Of two groups he looked at, in Namibia and Bolivia, less than 3% of foragers said they had trouble falling, or staying, asleep – a fraction of the up to 30% reported in industrial societies. Neither group had a word for "insomnia" in their languages.

"When I ask them 'Are they happy about their sleep? Are they satisfied with their sleep? Is sleep okay?' – however you try and get at this question – 9.5 out of 10 say, 'Yeah, I love my sleep'," Samson says. "Yet we know, quantitatively, that these foragers in these small-scale societies are sleeping less than those in the economically developed world.

"We have this narrative in the West [that] humans have never been more sleep-deprived," he adds. It's total rubbish, he says.

Samson is one of a growing number of researchers pushing against the idea of universal "rules" for exactly how much sleep we all must get. In one recent academic article, for example, researchers at the University of Oslo questioned the idea that we're experiencing an "epidemic of sleeplessness". They point out that laboratory experiments – which have given rise to the concerns that poor sleep inhibits health – are very different than real-life findings.

"Sleep need should be regarded as dynamic, with the potential to adapt in response to environmental circumstances," the researchers write. "This means that there is not an optimal amount of sleep for an individual across situations and times. Rather, sleep is a negotiable quantity that is affected by environmental, cultural, psychological and physiological factors, which must be balanced against competing needs and opportunities for various behaviours."

Believing there is only one "right" way to sleep isn't just, thus far, unfounded – it also can backfire.

That includes when we're trying to sleep. People with insomnia tend to have rigid beliefs about sleep (for example: "If I don't get seven hours, I'll feel terrible tomorrow") and often feel especially fearful of a poor night's sleep. They are also more alert towards sleep-related cues, such as watching the clock. All of these thoughts can increase arousal and anxiety at night, making sleep harder to attain. But they can even make a difference the next day, notes Tang. By making people more aware of how much they were awake the day after, it may exacerbate their feeling that they slept poorly – not only making them feel more tired, but also more worried about sleeping that night, continuing a "vicious cycle".

Often, however, these beliefs aren't actually based in fact. Those with insomnia tend to think that they require more sleep than is realistically necessary, for example, and to overestimate the impact of a poor night of sleep on their functioning.

As a result, traditional treatments for insomnia have tended to focus on cognitive-behavioural strategies to shift those thoughts and decrease arousal, such as practicing muscle relaxation.

This approach can help others struggling with sleep disturbances, too, like new parents, says Pamela Douglas, an Australian general practitioner, sleep researcher and founder of the Possums sleep intervention, an approach to parent-child sleep that has been adopted by health professionals around the world. She points out that most guidance on sleep for new parents emphasises focusing on tracking sleep duration and night wakes, for example. "Actually, we don't want to be looking at the clock or counting up hours," she says.

Beyond the particular beliefs we have about sleep, the problem is how attached to them we are, says Jason Ong, a long-time sleep researcher at Northwestern University who is now director of behavioural sleep medicine at sleep diagnostics company Nox Health in Atlanta, US.

"For people with insomnia, it's not just the fact that they think things like, 'I need eight hours of sleep or I'm not going to function the next day'. It's the degree to which they latch on to it," he says. His research has focused on using a mindfulness-based approach that encourages detaching from those thoughts.

Focusing too much on sleep doesn't just make it harder to get shut-eye. It also can mean feeling more fatigued the next day – even if we slept fine.

Ong recalls one patient who insisted that he needed six hours to function. When Ong pointed out a day in his sleep diary where he'd logged five, the patient told him that it had been daylight savings, but he didn't realise it. Only later, at the end of a gym session, did he realise he'd slept 5.5 hours, not 6.5. Then he felt exhausted.

"I said: 'Just the knowledge that you slept one hour or less changed how you felt the rest of the day?'," Ong says. "Is it really important how much sleep you got, or just how much sleep you think you got?"

This may also mean that the rapid rise of sleep tracking devices could backfire, warn researchers including Tang and Samson. Say we wake up feeling fine, but our smartwatch tells us we had a poorer night of sleep than average: we may now feel more tired than if we didn't have that information.

Some research bears this out. In one study, for example, people with insomnia were given feedback that researchers told them was from sleep data on a smartwatch. Unbeknownst to the participants, the feedback was fake. Half were told they'd slept badly, half that they'd slept well. When they reported back later in the day, the group who were told they'd slept poorly said they felt more fatigued, less alert and experienced a worse mood than the group who were told they'd slept well.

Feeling good about our sleep – even if it wasn't objectively great – doesn't just affect how tired we feel. It may even affect how well we perform. In one small recent study, participants in a laboratory were woken up after either five hours or eight hours of sleep, two nights in a row. But their clocks were set to make them think the opposite: those who slept five hours thought they'd slept eight, and vice versa.

When they were tested, the participants who slept five hours and thought they had slept eight had faster reaction times than those who slept five but were told the truth. Those who slept eight hours, but thought they slept five? They had slower reaction times than those who really had slept eight and were told so.

How we feel about a night of sleep also fluctuates throughout the day. "The way we think about our sleep can change, even after the sleep period," says Tang. In one study she co-authored, participants were asked multiple times throughout the day how they'd slept the night before. That sleep period didn't change – it was in the past – but their ratings of it did. In particular, if they were doing something they enjoyed, or physical activity, they suddenly had a more positive perception of how they'd slept the night before.

The importance of mindset doesn't mean we should adopt "toxic positivity", researchers caution. "We're not trying to get people to give themselves 'fake news'," Tang says. "But it's about being able to have that understanding, that nuance, that even if I don't get a very good night of sleep… I can still do things that I enjoy."

So, if you struggle with poor sleep, what can you do? All of the usual tips apply, experts say – for example, practising good sleep hygiene, which typically includes strategies like avoiding alcohol and caffeine and keeping a regular bedtime. (Learn some of the other ways you can improve your sleep according to science.)

But beyond that, try to adopt a less black-and-white approach to sleep. You might remind yourself of times that you didn't sleep perfectly but still had a good day, for example. Adopting a beginner's mindset can also help: not assuming that, because you've previously had a bad day after a poor night's sleep, that is what will always happen. Researchers including Tang, Douglas and Ong also advise not letting a bad night disrupt your life more than necessary by, say, cancelling plans. 

Tang's research also suggests focusing on things that boost your mood in the morning could also go a long way towards improving your evaluation of how you slept.

Understanding more about how sleep actually works can help, too, Tang says. Knowing that it's natural to have multiple awakenings during the night, for example, can make those wakes feel less frustrating. (Read more about the forgotten medieval habit of biphasic sleep.)

"I'm not saying that sleep is not important to overall physical health and mental health," Tang says. "But there is a culture where, when people talk too much about sleep duration, they have forgotten the fact that there are so many individual differences, and so many circumstantial aspects. And that is causing a lot of unrealistic expectation and guilt and disappointment for lots of people."

In fact, it has probably been making you feel more tired. How exhausting.

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