When was the last time you fell into a really deep sleep?

       Well if you check in at these lodgings in North Wales it really is one way you can be absolutely sure of the deepest sleep in the world.

       Set inside a former Victorian-era slate mine below the mountains of Snowdonia, these log cabins are being dubbed the world's deepest overnight accommodation.

       The four Deep Sleep cabins are a remarkable 1,375 feet below the earth’s surface - which is deeper than the height of The Shard in London which stands tall at 1,016 feet

       But it’s not for the faint of heart - as to reach your bed for the night you’re led by guides with Go Below on a 45-minute hike below the mountains.

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       The cabins feature battery-powered electric lighting, running tap water and a loo. The average temperature in the deepest chamber is around 10C.

       And if you do happen to have a bit of a panic - guides stay there too and can reassure any nerves.

       The Go Below website says that it is an “experience like no other on Earth”.

       It says: “Journey your way down through an abandoned Victorian slate mine to reach the remote off-grid adventure camp of Deep Sleep.

       “Set a staggering 1,375 vertical feet below the mountains of Snowdonia, this is the deepest underground sleep on the planet...by far.”

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       Deep Sleep runs once per week - on a Saturday night through to Sunday morning.

       The site adds that guests travel through ancient miners’ stairways and that there are decaying bridges to navigate.

       A complimentary expedition-style meal is also provided as well as a breakfast. The total price for two people in a private cabin is ￡375 and the total price for two people in a grotto is ￡575.

       Those who have made the “terrifying” journey have taken to travel review website Tripadvisor to rate their experiences.

       One said: "Wow what an amazing extreme experience.

       “Thrilling, challenging, terrifying, interesting, the hours flew by."

       Another said: "This was one of the best experiences of my life and I will never forget it!"