HOW TO SLEEP

the other day in the night , I couldn't to sleep, but I had to sleep because the next day I had an exam in the morning of biology and wanted to get up early to review a little in the morning. As couldn't sleep I started to look for methods to sleep in the internet, and I found one very good "4,7,8". It is to catch air for 4 seconds, hold them for 7 seconds and released for 8 seconds, this I did very well as 7 time already I was sleep.