For clarity there's regular Tylenol Extra Strength. This is a pain relief a 500mg with main ingredient being acetaminophen, known as Paracetamol outside US.

The recommended dose for an adult is 2x500mg.

There is also Tylenol PM, which is exactly as above however with added 25mg Diphenhydramine.

I'm a fairly big guy (189cm 86kg/6'2 190lb) so x2 is not really a heavy dose. I am most certainly not a pill addict, however I do find it very difficult to get constant sleep on planes.