Wellbeing expert Liz Earle has made it her mission to decode the secrets of healthy aging - and she has recently opened up about her number one priority... getting enough good quality sleep.

'I have to say I invest so much more time now in my sleep,' she said on Instagram. 'I prioritise it almost more than anything else and it’s gone right up my to do list.'

The best-selling author was sharing her thoughts after speaking to sleep scientist Dr Emily Bostock on her Age Better podcast. 'Want to reduce your risk of 172 diseases?' she said. 'Yeah me too. According to Dr Sophie Bostick, you just need to prioritise your sleep. It is the most powerful and most overlooked tool we have for healthy ageing.'

And she pinpointed her favourite pieces of advice:

'Deep sleep is when our brains clear out all the rubbish, including proteins linked to Alzheimers disease. So if you want to protect your brain for the long haul qulati matters as much as quantity.

'Secondly as Sophie says, our sleep gets less elastic with age. Back to back late nights in our 20s - fine. In our 50s - not so much.

'Hormones play a huge role... and replacing hormones absolutely can make a massive difference. For me, I slept terribly in my 40s and I put it down to stress. But that first night on Oestrogel [HRT], well, I’ve never slept better.'

But her favourite tip? 'Sky before screens. I say it all the time - real daylight, first thing. It resets our circadian rhythm. It makes good sleep so much easier.'

The science bears this out. Studies on pilots and cabin crew show excess fatigue is a real health issue; and shift work is linked to a range of health conditions. Paying atttention to our circadian rhythm really does count.