“You slept poorly, take a rest day.” I’ve spent months training and now finally I’m on the start line of my biggest race of the year – when my watch flashes up a most unwelcome message. I feel fine and I know – from the studies in this area – that one night’s poor sleep does not equate to poor performance. But that little message nudges my brain from confidence to concern: can I push hard for four hours despite a gadget designed to assess my physiological indicators telling me a decent performance is off the cards? Are our wearables too often using misleading, even counterproductive language?
