Only a decade ago, sleep was a relatively overlooked pillar of health. Most of us treated it as simple downtime – a period of inactivity in which we “recharged our batteries”. Medical advice at the time was quite basic: get eight hours or so a night and you would be fine.

That mindset shifted dramatically in 2017 when British neuroscientist Matthew Walker published the bestseller, Why We Sleep: Unlocking the Power of Sleep and Dreams. It was a wake-up call that brought the science of slumber to the masses, popularising the idea that sleep is not a passive state.

During deep sleep, the glymphatic system kicks in, acting like a waste-clearance service to flush out metabolic debris and proteins linked to Alzheimer’s disease.

Sleep was also crucial to memory consolidation and learning, Walker showed – and it suddenly became a new frontier in health and wellness.

A shift from quantity to quality

As sleep took centre stage, the wellness-minded started to take “sleep hygiene” seriously – such as creating the perfect dark, cool sanctuary and sticking to strict bedtime rituals. Trackers helped people chase the “perfect” sleep score. The “eight-hour rule” got more flexible, with experts recalibrating the goal to anywhere between seven and nine hours.