Whether it's that memory that makes you cringe from 10 years ago or a missed opportunity - we've all been kept up after hours as our body refuses to let us fall asleep.
And the more you think about not sleeping, the more you can't sleep.
The best method to tackle those restless nights comes as a 'military-proven technique.'
Designed to help soldiers fall asleep anywhere, this technique allows people to fall asleep in precisely 2 minutes after closing their eyes - and it has a 96% success rate.
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Fitness coach Justin Agustin - someone who appreciates a tight-knit regimen - shared the hack on TikTok.
'Now this technique was developed in the military to allow soldiers to fall asleep at any time, any place, even on the battlefield when the environment is extremely uncomfortable and a lot of noise is happening,' Agustin explained.
First things first, after lying down you need to have a calm body and 'systematically relax.'
This involves shutting down each part of your body from head to toe.
The expert describes going from the top down, so start by 'relaxing the muscles in your forehead,' working down to your eyes, cheeks and jaws - all whilst maintaining focus on your breathing.
Continue relaxing your neck before dropping your shoulders as low as you can, the expert says, and loosening your hands and fingers.
'Imagine this warm sensation going all the way from your head down to your fingertips,' Agustin continued.
Now it's time to take another deep breath: slowing exhaling and relaxing your chest and stomach, moving down to your thighs, legs, feet and toes.
Again, Agustin says to visualise the 'warm sensation going down from your heart all the way to your toes.'
Throughout this exercise, keep your mind clear, focusing solely on your breathing and relaxing your muscles.
Agustin suggests either imaging lying on a canoe surrounded by nothing but a blue lake and clear sky, or lying in a black velvet hammock in a pitch-black room.
If you find your thoughts wandering and getting distracted, the TikToker advises you to repeat the words 'don't think' over and over to yourself.
Now before you start thinking this is a quick fix, this technique is supposed to be practiced every night for six weeks in order to master it.
Happy sleeping!