Rules of Eternus (Mental Skill)

Meditation: By succeeding at a check, you are able to enter a self-induced trance for four hours. Meditation is so intense that it is almost a form of auto hypnosis. This allows you to ignore normal fatigue or exhaustion as if you had slept, after which time you must either rest or meditate again.

Note: For every one hour of meditation you receive two hours of rest equivalent to sleep.