Hi, in the main menu, in the top right corner there is a manual with the instructions, but I can explain it to you.
You win by keeping the subject 12 days without sleeping (the fatigue never drops to 0) and doing 6 reports, to make it, you need to do a test either sound or light, you can only do 1 report per day, the light test keeps on draining sanity while its on, so you need to turn it on and off. The gas its a mechanic that makes the fatigue to go down slower, but you have a limit per day (50).