There's nothing worse than a restless night spent tossing and turning and trying not to look at the clock.
But an old sleep technique reportedly used by the US army to help them fall asleep in less than peaceful situations - such as on battlefields - has been unearthed and published online.
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The secret is detailed in the book Relax and Win: Championship Performance, which was first published in 1981 but has recently gained traction online after Joe.co.uk republished it.
"The US Navy Pre-Flight School developed a scientific method to fall asleep day or night, in any conditions, in under two minutes," the book reads.
"After six weeks of practice, 96 percent of pilots could fall asleep in two minutes or less. Even after drinking coffee, with machine gunfire being played in the background."
Here's how to do it:
- Relax the muscles in your face, including tongue, jaw and the muscles around the eyes
- Drop your shoulders as far down as they'll go, followed by your upper and lower arm, one side at a time
- Breathe out, relaxing your chest followed by your legs, starting from the thighs and working down
You should then spend 10 seconds trying to clear your mind before thinking about one of the three following images:
- You're lying in a canoe on a calm lake with nothing but a clear blue sky above you
- You're lying in a black velvet hammock in a pitch-black room
- You say "don't think, don't think, don't think" to yourself over and over for about 10 seconds