The Science Behind A Good Night's Sleep: Sleep-Wake Cycles Explained

Often when people come into our sleep clinic seeking treatment, they share ideas about healthy sleep.

Many think when their head hits the pillow, they should fall into a deep and restorative sleep, and emerge after about eight hours feeling refreshed. They're in good company – many Australians hold the same belief.

In reality, healthy sleep is cyclic across the night, as you move in and out of the different stages of sleep, often waking up several times. Some people remember one or more of these awakenings, others do not. Let's consider what a healthy night's sleep looks like.

Adults usually move through five or six sleep cycles in a night, and it is entirely normal to wake up briefly at the end of each one. That means we might be waking up five times during the night. This can increase with older age and still be healthy. If you're not remembering these awakenings that's OK – they can be quite brief.

What does getting a ‘good' sleep actually mean?

You'll often hear that adults need between seven and nine hours of sleep per night. But good sleep is about more than the number of hours – it's also about the quality.

For most people, sleeping well means being able to fall asleep soon after getting into bed (within around 30 minutes), sleeping without waking up for long periods, and waking feeling rested and ready for the day.

You shouldn't be feeling excessively sleepy during the day, especially if you're regularly getting at least seven hours of refreshing sleep a night (this is a rough rule of thumb).

But are you noticing you're feeling physically tired, needing to nap regularly and still not feeling refreshed? It may be worthwhile touching base with your general practitioner, as there a range of possible reasons.

Common issues

Sleep disorders are common. Up to 25% of adults have insomnia, a sleep disorder where it may be hard to fall or stay asleep, or you may wake earlier in the morning than you'd like.

Rates of common sleep disorders such as insomnia and sleep apnoea – where your breathing can partially or completely stop many times during the night – also increase with age, affecting 20% of early adults and 40% of people in middle age. There are effective treatments, so asking for help is important.

Beyond sleep disorders, our sleep can also be disrupted by chronic health conditions – such as pain – and by certain medications.

There can also be other reasons we're not sleeping well. Some of us are woken by children, pets or traffic noise during the night. These “forced awakenings” mean we may find it harder to get up in the morning, take longer to leave bed and feel less satisfied with our sleep. For some people, night awakenings may have no clear cause.

A good way to tell if these awakenings are a problem for you is by thinking about how they affect you. When they cause feelings of frustration or worry, or are impacting how we feel and function during the day, it might be a sign to seek some help.

We also may struggle to get up in the morning. This could be for a range of reasons, including not sleeping long enough, going to bed or waking up at irregular times – or even your own internal clock, which can influence the time your body prefers to sleep.

If you're regularly struggling to get up for work or family needs, it can be an indication you may need to seek help. Some of these factors can be explored with a sleep psychologist if they are causing concern.

Can my smart watch help?

It is important to remember that sleep-tracking devices can vary in accuracy for looking at the different sleep stages. While they can give a rough estimate, they are not a perfect measure.

In-laboratory polysomnography, or PSG, is the best standard measure to examine your sleep stages. A PSG examines breathing, oxygen saturation, brain waves and heart rate during sleep.

Rather than closely examining nightly data (including sleep stages) from a sleep tracker, it may be more helpful to look at the patterns of your sleep (bed and wake times) over time.

Understanding your sleep patterns may help identify and adjust behaviours that negatively impact your sleep, such as your bedtime routine and sleeping environment.

And if you find viewing your sleep data is making you feel worried about your sleep, this may not be useful for you. Most importantly, if you are concerned it is important to discuss it with your GP who can refer you to the appropriate specialist sleep health provider.

Amy Reynolds, Associate Professor in Clinical Sleep Health, Flinders University; Claire Dunbar, Research Associate, Sleep Health, Flinders University; Gorica Micic, Postdoctoral Research Fellow, Clinical Psychologist, Flinders University; Hannah Scott, Research Fellow in Sleep Health, Flinders University, and Nicole Lovato, Associate Professor, Adelaide Institute for Sleep Health, Flinders University

This article is republished from The Conversation under a Creative Commons license. Read the original article.