what is the quickest way to put yourself to sleep?

are there "reverse" smelling salts which instead of waking you up, put you to sleep?

i need to go to sleep almost instantaneously for an experiment i'm doing, and i'm looking for the best way.

i've thought of sleeping tablets but they may take a while. and there is ether. but i dont know if you can buy that over the counter. plus, that may be a bit extreme, i dont know of the health risks of that.


so, can someone please make a suggestion.

thanks