Back in the 1980s I got really sick with the strain of the flu that causes body aches. I hurt so bad I hadn't been able to sleep for 48 hours and I felt like I was dying. I figured that if I had to go another night without sleep it would be fatal. So, I started thinking about how I could get some sleep. I then remembered I had part of a prescription of Tylenol 3, 5 grains of codeine, left from when I had torn up an ankle playing basketball a year or so earlier. I found I had 3 left. I took all three and went and stretched out on my recliner. I don't know how long it took me to fall asleep but it wasn't long.
I woke up between 7 and 8 in the morning and felt great. I told my wife that 15 hours of sleep sure did wonders and she laughed at me. What I'd really done was slept 40 hours straight. But I was well. I had zero symptoms of the flu and went to work that morning.
Sleep is what cured me. Our body can heal itself from serious issues if we give it a chance to rest and recuperate and that's exactly what that codeine did for me.