**The hack
**Taking an eight-minute nap during the day, as recommended by a retired US Navy Seal.
**The test
**According to former Navy Seal Jocko Willink (great name), eight minutes is the ideal nap time: you wake up rested, without feeling groggy. TikTok is awash with sleep hacks, but might this one work? According to Willink, you have to “elevate your feet above your heart and then set your alarm for eight minutes, and afterwards he feels like “superman”.