Opposite conditions vs NOT question

I have a handful of rules that say things like

(Chris not present
OR
(Chris present
AND
Chris Sleep on))

Right now I have "Chris not present" and "Chris present" both in the condition list, and use them separately in the rule. Is there any difference between doing this vs having a single condition (Chris present) and using the NOT operator?

So instead of the above, I'd have
(NOT(Chris present)
OR
(Chris present
AND
Chris Sleep on))

Is the latter more efficient than the former since there's one fewer condition? Does it make any difference either way?