Fatigue (rest and sleep)

Players and Game Judges often forget fatigue, but every character, and especially the spell caster who is seldom in fine physical shape, needs rest after hard exertion and sleep after long stretches of activity of 8 hours or more. Constitution sets how much of each is required.

After strenuous activity a character with CON 20 or more hardly needs rest at all. CON 18-19 needs 5 minutes for every 2 hours, CON 17 needs 5 minutes an hour, CON 15-16 needs 10 minutes an hour, CON 10-14 needs 15 minutes an hour, and CON 9 or less needs 20 minutes an hour. Each rest period skipped or cut short costs a point of Constitution, which only sleep brings back.

Sleep works the same way. With CON 20 or more a character can go a week or longer without sleep and suffer nothing; CON 19 can skip up to two nights and CON 18 one night. Below that the minimum is 1 hour at CON 17, 2 hours at 15-16, 4 hours at 10-14 and 6 hours at 9 or less. Falling short costs a point each of CON and INT, since the character grows drowsy.