"I don't need a monitor to tell me how I sleep, I know the minute I open my eyes," my friend Tracy told me recently, while fidgeting with her Oura ring.

She wears the chunky band to keep track of her steps and meet her goal of walking 10,000 steps a day. It's more accurate than her phone, which isn't on her 24/7.

She's one of millions who now rely on wearable tech for health data - and this week, Apple made a move that will give many Apple Watch owners back a key health feature they've been missing.

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Wearable technology has exploded in recent years, with people now using rings, bracelets, and smartwatches to track far more than steps or sleep.

The devices can monitor heart rate anomalies, menstrual and ovulation cycles,

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