Sleep quality vs sleep quantity: Why more sleep isn't always better

Most of us have heard the magic number: aim for seven to nine hours of sleep each night.

But have you ever spent eight hours in bed and still woken feeling exhausted? Or perhaps you've had a slightly shorter night's sleep yet felt surprisingly refreshed the next day?

That's because when it comes to sleep, the number of hours you get is only part of the story.

Good sleep is built on three pillars: quantity, quality and consistency. While getting enough sleep matters, the quality of that sleep and the regularity of your sleep routine can be just as important for your health and wellbeing.

It's not just about the hours

Sleep quantity refers to how much sleep you get. For most adults, experts recommend around seven to nine hours each night, although individual needs vary.

However, sleeping for long periods doesn't automatically mean you're getting restorative sleep.

"Quality" sleep means your body can move naturally through the different stages of sleep without frequent disruption. Throughout the night, we cycle through lighter sleep, deep sleep and REM (rapid eye movement) sleep, with each cycle lasting around 90 minutes. These stages play different roles in physical recovery, memory consolidation and emotional processing.

If you're waking repeatedly during the night, you may not be completing these cycles, even if you've spent plenty of time in bed.

This helps explain why some people can sleep for eight hours and still feel tired, while others feel alert and refreshed after less sleep.

Why sleep changes with age

Many older Australians worry that they're not sleeping as deeply or as long as they once did.

The reassuring news is that this is a normal part of ageing.

As we get older, we naturally spend less time in deep sleep and may wake more frequently during the night. Sleep often becomes lighter and more fragmented than it was in younger adulthood.

That doesn't necessarily mean something is wrong.

The more useful question is often: how are you functioning during the day? If you feel alert, can concentrate, and are able to enjoy your usual activities, your sleep may be meeting your body's needs even if it looks different from what it did decades ago.

The overlooked role of consistency

Consistency is the third ingredient of healthy sleep, alongside quantity and quality.

Our bodies operate on an internal clock known as the circadian rhythm. This body clock helps regulate when we feel sleepy and when we feel awake, largely in response to natural light.

When bedtimes and wake-up times vary dramatically from day to day, that internal rhythm can become disrupted.

Many people try to compensate for poor sleep during the week by sleeping in on weekends. While an occasional sleep-in won't do any harm, constantly shifting sleep schedules can make it harder for the body to establish a predictable sleep-wake pattern.

Research is increasingly suggesting that sleep regularity itself may be an important contributor to long-term health.

In other words, going to bed and waking up at roughly the same time each day may be just as valuable as chasing a particular number of hours.