Your mental state is your current frame of mind, and how clearly and
realistically you view your surroundings. Mental states can be affected by
prolonged combat, hunger, thirst, or poison. Certain combat spells can
affect your mental state. If you are affected by one of the above for a
period of time, your mental state will begin to deteriorate, and you will not
view your surroundings as they truly are. You may begin to hallucinate, or
become too lethargic to function, and your general abilities will be
affected. In extreme cases you may collapse from exhaustion or enter a
delirious coma.
To restore your mental state, you may need to rest (resting and sleeping will
speed your recovery), eat, cure whatever poison afflicts you, etc. Note that
if you are malnourished your state will not improve, even with sleep, until
you have fed and/or quenched your thirst. The spell revive helps improve
mental state.
Your current mental state is displayed by the 'affected' command.