You will have to go through customs and immigration so you can't stay airside. If transit or regular security still open you might be able to go through and might not be kicked out later by security. A reddit user says, "terminal one, if you go all the way to the left (when entering it from outside), or essentially as far East as you can go on the check-in level, there are long lounge chairs which are setup there and people sleep on them pretty often. That’s where I went even though my morning flight was leaving from terminal 3."