Turns out the right kind of “brain washing” is very good for you
Most people know that sleep helps us feel more alert, less irritable, and better able to concentrate. What many people don’t realise is that while we sleep, the brain is doing something essential for long-term health: it is clearing away waste products that build up during the day.
This discovery has changed how we need to think about sleep. Rather than being “downtime” for the brain, sleep is now understood as an active and vital period of brain maintenance.
The Brain’s Cleaning System
Unlike the rest of the body, the brain does not have the lymphatic system to remove waste. Instead, it relies on a specialised process known as the glymphatic system. This system uses cerebrospinal fluid, the fluid that surrounds the brain, to wash through brain tissue and remove metabolic by-products produced during waking hours.
Research has shown that this cleaning system works most efficiently during sleep, particularly during deep, slow-wave sleep. When we enter this stage of sleep, brain cells slightly shrink, creating more space between them. This allows fluid to flow more freely and flush out waste products such as beta-amyloid and other proteins that are a normal part of brain metabolism but potentially harmful if they accumulate.
In simple terms, good sleep gives the brain the space and conditions it needs to take out the rubbish.
Why Sleep Health Matters
Both the number of hours you spend asleep and the quality and continuity of your sleep may play a role in supporting brain health. Fragmented sleep, frequent awakenings, or very light sleep may limit the brain’s ability to engage in this nightly clean-up process. Interestingly, how much you think you sleep can also play a role in brain health and cognitive function.
“Sleep is a powerful tool we have to support health and wellbeing, yet it’s often one of the first things people sacrifice,” says UWA Clinical Associate Professor Melissa Ree, Director of Sleep Matters. “What excites us as clinicians is that when we treat insomnia properly, we’re not just helping people feel better day to day. We’re potentially supporting long-term mental and physical health, potenitally including brain health, in meaningful ways.”
Insomnia and the Brain
Chronic insomnia is not simply a problem of feeling tired. It is a condition that affects how the brain functions both day and night. People with insomnia often spend more time in lighter stages of sleep and less time in deep, restorative sleep, which may reduce opportunities for effective glymphatic clearance.
Importantly, insomnia is highly treatable. Cognitive Behavioural Therapy for Insomnia, known as CBT-I, is considered the gold-standard treatment and is recommended by international clinical guidelines. CBT-I works by improving sleep quality, sleep timing, and sleep depth rather than relying on medication to force sleep.
Ongoing Research at UWA
Clinical Associate Professor Ree has been involved in clinical research at The University of Western Australia, examining how CBT-I may improve cognitive function and broader markers of brain health in adults with chronic sleep difficulties. This work builds on international findings suggesting that improving sleep quality can lead to measurable improvements in attention, memory, and daytime functioning.
While these results are still being analysed, the emerging evidence supports a hopeful message: treating insomnia is not just about getting through the next day, but about supporting the brain over time. Watch this space for future research outcomes as this work progresses.
What This Means for You
You do not need to aim for “perfect sleep” to support your brain. Consistent, reasonable-quality sleep is what matters most. If sleep is frequently broken, unrefreshing, or hard to initiate, it is worth taking seriously rather than pushing through. Waking up briefly a few times overnight is normal, as is the odd poor night of sleep.
At Sleep Matters, we take a science-informed, compassionate approach to assessing and treating sleep difficulties. Our work focuses on understanding the underlying patterns affecting sleep and using evidence-based interventions to help people sleep more deeply, more reliably, and with greater confidence.
A Reassuring Note for People with Insomnia
If you live with insomnia, reading about the importance of sleep can sometimes increase worry rather than reassurance. It’s important to know that the brain is resilient, and it does not require “perfect” sleep to stay healthy. Occasional poor nights, lighter sleep, or broken sleep do not undo the benefits of sleep overall. What matters most is the long-term pattern, not any single night. Evidence-based treatments like Cognitive Behavioural Therapy for Insomnia focus on reducing sleep effort and sleep-related anxiety, because paradoxically, trying harder to sleep is often what keeps insomnia going.
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