ScienceAugust 20, 2021

Sleep scientists answer your most burning sleep questions


Sleep Week: The group of sleep geniuses from the Sleep/Wake Research Centre answer their most frequently-asked questions about catching Zzz’s.

All week, The Spinoff is tossing and turning through a range of perspectives on sleep – read more Sleep Week content here

The Sleep/Wake Research Centre has been researching sleep, waking function, and circadian rhythms for over 20 years. Central to our work are aims around achieving a greater understanding of the relationships between sleep and waking functions and how they are regulated. With such understanding we are in a better position to support health, safety, productivity for all. Much of our work is around sleep changes across the lifespan, social inequities in sleep health among New Zealand populations, and fatigue. 

Our current projects include supporting and understanding the sleep of mothers, babies and children; sleep changes with aging, dementia, and caregiving; and managing fatigue risk for nurses and aviation workers. We also work closely with industry groups and regulatory agencies to develop evidence-based solutions for fatigue and shift-work management, policy and regulation and contribute expert scientific evidence in accident investigations.

We often give presentations as a part of our research consultation or to share key findings from projects and are always asked all sorts of interesting questions on the topic of sleep. So, as a part of The Spinoff’s Sleep Week, we thought we’d compile some of the most frequently asked questions. 

Do we really need eight hours of sleep a night? 

Sleep guidelines recommend that adults get seven to nine hours of sleep to function at our best and stay well. Research shows that, compared to people who get eight hours of sleep per night, those who get less than seven hours sleep are slower to react, less coordinated, make poorer decisions, and have worse mood.  Furthermore, sleeping less than six hours sleep each night has been linked to higher risks of putting on weight, developing type two diabetes and heart disease, and suffering a stroke. We also see these health problems for those consistently having very long sleep. Our surveys in Aotearoa have shown that most of us do get between seven and nine hours of sleep on average, although about a quarter of New Zealanders report getting six hours or less.

Can I make up my lost sleep at the weekend?

Shifting the timing of our sleep between weekdays and weekends is not so good for our health. The weekdays can be full on with the commitments of work and family and sleep is often sacrificed  with the belief that we can catch up on sleep at the weekend. Unfortunately, trading and banking sleep doesn’t quite work like that. Research shows that missing out on sleep during the week leads to gradual decline in our functioning. Sleeping in for two or three days might make us feel much better, but we still don’t seem to return to the optimal levels of functioning we would experience if we had been routinely getting seven to nine hours of sleep each night. This can lead to a cumulative sleep debt that rolls over into the next week. 

An insomniac plots their next sleep hack. Photo: Getty (additional design by Tina Tiller)

Is sleep an ‘offline’ state?

The traditional view is that when we sleep, we go into ‘rest’ mode. But this is outdated, and we now know that the brain is actually very active during sleep (some parts of the brain are even more active than in wakefulness). Such activity tells us that sleep is playing an important functional role leading to many theories on the roles of sleep. Research has found that, while we sleep, growth hormones are secreted and processed, neural connections are strengthened supporting learning and storage of memories, and harmful proteins are processed and flushed from the brain. Sleep also facilitates the processes necessary for optimising our immune system and metabolism of food. So together, sleep provides a time for the body and mind to recalibrate and optimise waking function and health. 

If I wake up at night does it mean I have a sleep problem?

Historically (before artificial lighting), people would have a longer time in bed which followed the natural cycle of light and dark. Having a couple of hours of wakefulness in the middle of the night was not uncommon. However, people would still achieve a decent eight hours of sleep overnight. In today’s society, we strive to get our sleep in a consolidated block so it can feel problematic when we wake up at night. But it is quite normal to wake a few times overnight, roll over and go back to sleep. If you experience frequent awakenings (three or more per night) or spend long periods of time awake (20+ minutes), it may be time to work on your sleep habits or speak to a health professional about your sleep. Certainly, if you think you have a medical issue that is disrupting your sleep have a chat with your GP. 

Can I turn myself into an early bird?

While getting up early is tempting to get ahead on the day and be (or feel) more successful, this only really works if you also got enough sleep the night before and are truly a natural ‘early bird’. Natural early birds (morning types) consistently go to bed and wake earlier than the average person, and do not need to rely on an alarm to wake early. While we can try to shift our sleep back a little each evening, it can be challenging to change your body’s preferred sleep timing and keep to the new early timing.

Furthermore, there is no evidence that those who choose to or find themselves waking earlier function better than those who wake at usual times. Optimal functioning comes with sleeping according to your natural timing and getting enough sleep, which then allows us to perform well during the day. It can be hard to work out your natural sleep timing, but we often get a sense when we have less restrictions on our day. So, when on holiday or perhaps during Covid-19 lockdowns, you may have noticed your sleep timing and preferences drifting to something more naturally fitting for you.  

Mr Bean knows the importance of seven to nine hours sleep a night. Photo: Youtube

Do we need less sleep when we’re older? 

As we progress through childhood, adolescence and adulthood, our sleep structure and timing changes. This reflects some of the functions of sleep, for example the importance of sleep for physical growth, learning and performance.  Once we reach older adulthood sleep often becomes lighter in quality, so we are more likely to wake up at night. Some older adults also report waking earlier in the morning than when they were younger. Older adults seem slightly more resilient to the effects of minor sleep loss compared to younger adults, which might be why a common belief is that we need less. But the recommendation of around eight hours of sleep still holds to feel and function at our best when we’re older. This can be challenging with some of the medical conditions or commitments that we might have with ageing. But remember, sleep doesn’t have to happen all at once, a planned day nap can help.

What is the point of dreams?

Humans have a longstanding fascination with dreams, as evidenced in historical art and therapies. Dreaming experience can change at times of physical and mental illness and some consider that working with dreams in therapy can have a healing effect. There are several theories as to why we dream. Psychoanalysts theorise that dreams serve to maintain a balanced psyche by representing content from the unconsciousness, while evolutionary and developmental theories suggest that dreams allow us to rehearse behaviours in a safe space.

Since the discovery of Rapid Eye Movement sleep (REM) and its association to dreaming experience, our understanding of how the changes in the brain and dreaming are associated has grown. Contemporary neurological work has found that, while dreaming, areas of the brain associated with emotional processing, learning and memory are very active and neural networks are strengthened. When people are deprived of REM dreaming, their ability to retain new information or manage complex waking situations are impaired, indicating a key function of dreaming in mental health.

Coffee: Not a good idea before bed. Photo: Getty.

What about caffeine? I drink coffee right before bed and never had trouble sleeping…

Caffeine is present in lots of different drinks and foods. Coffee, tea, chocolate and many soft drinks contain it. Caffeine affects our brain and behaviour by restricting chemicals in the brain that help us sleep. Many people use caffeine to feel more alert, but it can also increase feelings of anxiety. We need to be careful when and how much caffeine we consume. It is absorbed quickly into the bloodstream and, although we tend to be aware of the effects for just an hour or so, the impact can actually last at least three to seven hours. This means that, even if you are able to fall asleep after consuming caffeine, you are likely to wake up more,,or have less deep sleep than if you were caffeine free in the hours before bed. 

Why is my teenager so lazy?! 

Many of us will be familiar with a pattern of struggling to get teenagers out of bed in the morning and that they complain of feeling more tired in the day. While this may seem like laziness, teenagers’ biology means that their circadian body clock tends to shift to a later sleeping time. This makes it more difficult for them to fall asleep or wake up at what are considered appropriate times for school and other activities. The common teenage lifestyle can add to these sleep changes. Increasing independence, social activity, social media and the demands of school or work can mean that sleep is shortened. 

Research from New Zealand shows that teenagers have about a one and a half hour difference between bedtimes on school nights and weekends, and almost a quarter are not getting the recommended eight to nine hours of sleep per night. This is important because sleep plays a role in learning, memory, and attention so when teenagers have insufficient sleep this can impact academic performance, mood, and risk-taking behaviours. It is important to put in place good sleep habits during adolescence so as not to develop long standing sleep problems into adulthood. 

I bought a fancy sleep tracker, why isn’t my sleep improving?

Traditionally, sleeping was more a private affair, but sleep aids and digital health trackers have become a booming industry. Using wrist-worn devices and phone apps, people can record the timing and ‘quality’ of their sleep and compare themselves to others or the recommended averages. But many devices on the market have not been validated for accurately measuring sleep, particularly sleep quality and stages.

Furthermore, the incessant self-monitoring of sleep can actually make our sleep quality worse. “Orthosomnia is a newly defined sleep disorder characterised by an unhealthy quest for perfectionistic sleep and optimal daytime functioning by self-monitoring and quantifying sleep. Like the bathroom scales we use for measuring weight and defining diet goals and success; sleep trackers, apps, and remedies market sleep as a modifiable behaviour without necessarily providing the tools needed to improve it.

For more information on sleep research, sleep tips, or sleep disorders check out the Sleep Wake Research Centre, Sleep Foundation, or Australian Sleep Health Foundation, or the regular podcasts at Sleep Junkies and Sleep Hub  

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