sane

adjective

Pronunciation: /seɪn/

Etymology: Learned borrowing from Latin sānus (“healthy; sane”). Doublet of sound.

Being in a healthy condition; not deranged; thinking rationally.
“a sane mind”
Mentally sound; possessing a rational mind; having the mental faculties in such condition as to be able to anticipate and judge the effect of one's actions in an ordinary manner.
“a sane person”
“Shepard: What's wrong with your assistant? Dr. Warren: Manuel has a brilliant mind, but he's always been a bit... unstable. Genius and madness are two sides of the same coin. Dr. Manuel: Is it madness to see the future? To see the destruction rushing towards us? To understand there is no escape? No hope? No, I am not mad. I'm the only sane one left! Dr. Warren: I gave him an extra dose of his meds after the attack.”
Rational; reasonable; sensible.
“Try to go to bed at a sane time before your exams.”