With the City2Surf on this weekend, Sydney is officially in peak training mode. Everywhere you look, someone’s obsessing over their kilometre splits, debating shoe choices or plotting their strategy for Heartbreak Hill.
According to sleep and cardiovascular experts, the runners smashing their goals for city2surf this year might be the ones doing something a little less Instagrammable: sleeping properly. It turns out the real gains aren’t made pounding the streets… they’re made overnight, while your body actually does the repair work.
The recovery gap is real:
Chronic sleep deprivation doesn’t just leave you groggy on your morning run, it quietly sabotages your training. Poor sleep and inconsistent recovery tracking are linked to a higher risk of injury and can stunt the aerobic gains you’ve been working so hard for, whether you’re lacing up for your first fun run or chasing a personal best.
The catch is that most of us don’t clock it as a training issue. We’ll happily overhaul our diet, invest in new runners, or download the latest training app, but skip on sleep without a second thought. It’s the one variable that doesn’t show up on a leader board, so it’s the easiest to ignore, right up until it catches up with you a fortnight out from race day.
Training tired makes your heart work overtime:
Dr Pierre Escourrou, professor of physiology at the University Paris Sud Saclay, says that when you’re under-slept, your heart has to work exponentially harder to do the same job it would normally handle with ease. Your resting heart rate creeps up, your heart rate variability drops and your body simply isn’t operating from the same baseline.
That means your pacing suffers and your oxygen efficiency takes a hit, even if your legs feel technically “fine” on the day. Essentially, you’re running the same course with less fuel in the tank and your body is compensating in ways you can’t always feel until you’re several kilometres in.
For anyone chasing a personal best this year, that’s a big deal. A tired cardiovascular system doesn’t just make the run feel harder, it can add real time to your finish, no matter how solid your training block has been.
Deep sleep is when the repair work happens:
Sleep isn’t one long, uniform block, it moves through cycles and deep sleep is where the real physical repair happens. Skipping or shortening those deep sleep cycles means your muscles miss out on crucial repair time, which is exactly the kind of thing that can lead to those sudden, sneaky stress fractures cropping up mid-training block, often catching runners off guard because nothing “went wrong” in a single session.
It’s not always about how many kilometres you’ve logged, it’s about how well your body has been allowed to bounce back between sessions. Two runners can follow the identical training plan and end up in very different places, purely based on how well they’re recovering overnight.
Ditch the rigid training plan, follow your data instead:
Rather than sticking religiously to a generic training schedule pulled off the internet, Dr Escourrou goes on to say that tracking your resting heart rate and sleep quality is a far more reliable guide to how your body is actually coping. A spike in resting heart rate or a run of poor sleep can be an early sign to dial things back, well before an injury forces you to.
This is where wearable tech comes in handy. Devices like the Withings ScanWatch 2 are designed to track exactly this kind of data, monitoring sleep stages and resting heart rate alongside your training, so you get a genuine read on recovery rather than training blind and hoping for the best. For anyone juggling a demanding job, a social life and a training block, that kind of visibility takes a lot of the guesswork out of knowing when to push and when to back off.
Dr Escourrou’s own recovery rules:
Dr Escourrou has shared some of his own practical advice for better sleep and a couple of his rules are especially relevant heading into race week. He recommends leaving at least four hours between your last bout of exercise and bedtime, since training too close can actually disturb your sleep rather than help it. He’s also a strong advocate for keeping a consistent bedtime and wake-up time, arguing that a predictable routine trains your body to fall asleep and wake up more easily, rather than fighting against it.
And when it comes to the bedroom itself, he points to a cooler room, ideally on the cooler side rather than warm, as one of the simplest ways to help your body settle into deep sleep faster. For runners juggling early alarms and evening training sessions, that timing advice in particular is worth building into the final stretch of your program.
What this means for your final weeks of training:
With race day closing in, the temptation is always to squeeze in extra kilometres or an additional hill session. But if the goal is to actually feel good crossing that finish line, prioritizing sleep in these final weeks may do more for your performance than another training run. That means protecting your bedtime the same way you’d protect a long run, cutting back on screens before bed, and treating a full night’s sleep as part of the taper, not something separate from it.
Your Heartbreak Hill PB might just come down to how well you slept the night before, not how many extra kilometres you squeezed in this week. As Dr Escourrou’s research suggests, recovery isn’t the boring add-on to training, it’s the part that actually makes the training work.
