Biohacking sleep: what you need to know about the ‘glymphatic reset’
For many of us, sleep doesn’t always deliver the fresh start we expect. We all have those mornings where we wake up groggy and drained, despite getting our eight hours of rest.
So why is this? Well, the answer may lie deep in the brain, where a silent clean-up team gets to work once we drift off: the glymphatic system. Its job is to sweep away debris and restore mental clarity for the day ahead. But here’s the catch – this cleansing cycle only really hits its stride when our sleep is at its best.
So what exactly is this system – and why does it matter even more in midlife? Here’s what you need to know.
What is the glymphatic system?
First identified just over a decade ago, the glymphatic system is only now beginning to reveal how vital it is for brain health.
“The glymphatic system is like your brain’s night-time cleaning crew,” explains Kathryn Pinkham, founder of The Insomnia Clinic. “It works while you sleep to wash away waste and toxins that build up during the day.”
The quality of our sleep is what makes the difference. This system works best in deep, restorative stages, when it can properly cleanse the brain and reset the mind for the next day. But what does that actually look like in practice?
The science of sleep
Seven or eight hours in bed doesn’t always guarantee a reset. What really matters is the quality of our sleep.
“The glymphatic system is most active during the deeper stages of non-REM sleep, particularly slow-wave sleep,” explains Kathryn. “This is when the brain’s cells shrink slightly, allowing cerebrospinal fluid to flow more freely and clear away waste products.” Think of it as the brain giving itself extra elbow room to do a proper deep clean.
A 2024 Nature Neuroscience study highlighted just how crucial this stage is. Researchers found that people who spend more time in slow-wave sleep have stronger glymphatic activity and healthier brains over time. It’s a reminder that deep sleep isn’t just about feeling rested the next day – it’s an investment in our long-term health.
But Kathryn points out that deep sleep isn’t the whole picture. “Good-quality sleep involves cycling naturally through all stages – light, deep, and REM – multiple times a night,” she says. Deep sleep drives restoration, while REM supports memory and emotional balance.
Modern life can make that cycle easy to disrupt, from late-night scrolling to restless 3am wake-ups. And in midlife, the challenge is even greater. “During midlife and menopause, fluctuating and declining hormones – particularly oestrogen and progesterone – can disrupt sleep in several ways” says Kathryn.
Progesterone normally has a soothing, sleep-promoting effect, while oestrogen helps regulate temperature and mood. As both decline, night wakings, hot flushes, and increased anxiety become common – cutting into the very stages when the glymphatic system works hardest.
Over time, this disruption leaves the brain’s cleaning crew unable to finish its work, making us feel less focused, more reactive, and emotionally drained.
And here’s the twist: the glymphatic system isn’t only supported at night – it’s primed long before our heads hit the pillow.
Why our day shapes our night
Supporting the glymphatic system isn’t just about sleep itself – it starts much earlier.
“Your body clock is set by light exposure, activity levels, even when you eat and use the toilet. All of these daytime factors influence how good the quality of our sleep is,” explains Kathryn.
If we spend most of the day indoors, our brains miss the daylight cues needed to set our internal rhythms.
“Getting outside in natural daylight, especially in the morning, helps anchor that rhythm,” says Kathryn, adding that it also lifts mood and reduces stress.
What we drink also plays a role. A morning coffee or one in the early afternoon is usually fine, but too much later in the day can delay deep sleep. Alcohol, meanwhile, “disrupts the deeper, more restorative stages of sleep,” Kathryn notes, leaving us feeling more tired the next day.
Stress matters too. When we spend the day on high alert, tension often lingers in the body at night, keeping our brains switched on.
Think of the daytime as setting the tone. To carry it through into truly restorative sleep, we need some deliberate steps – the kind Kathryn builds into her glymphatic recharge toolkit.
Your glymphatic recharge toolkit
For Kathryn, the foundation of supporting the glymphatic system and better sleep isn’t rituals or routines, but resetting the body clock.
That’s why she recommends CBT-I (cognitive behavioural therapy for insomnia) – an evidence-based approach that retrains your brain and body to sleep better by strengthening sleep drive, resetting rhythms, and reducing night-time anxiety. In short, it creates the conditions the glymphatic system needs to work at its best.
Go to bed later, not earlier
Heading to bed too soon often backfires. Waiting until we’re properly sleepy – and pairing it with a steady wake-up time – builds a stronger drive for rest. That way we can fall asleep faster, stay asleep, and reach the deeper stages of sleep our brains need.
Don’t stay in bed awake
If we’re lying there restless for more than 15–20 minutes, it’s key we get up and do something calm in low light. This helps stop our brains from linking the bed with frustration or racing thoughts, so it learns to associate it only with rest.
Deal with worries in the day, not at midnight
Set aside 10–15 minutes earlier in the day to jot down and process concerns. It helps to tell the mind that they’ve been dealt with – a small signal that makes it easier to switch off at night.
Once these foundations are in place, supportive habits – hydration, natural daylight, balanced nutrition, gentle wind-downs – really start to work. Without the body-clock reset, they only go so far. With it, they supercharge the brain’s ability to clear, repair, and reset.
When the glymphatic system runs smoothly, mornings feel lighter, moods steadier, and memory sharper. Sleep isn’t passive; it’s one of the most powerful things our bodies do.
