How long does it take for a character to gain the Fatigued condition? I should think that 12-14 hours without sleep would do it.
There are no rules for sleep.
One of the Carrion Crown adventures has some suggested rules for sleep deprivation.
This has come up before and the Golems at Paizo have said (in a rather rude way, imho) that sleep should be handled by 'common sense.'
That's what I could find from the pathfinder site...The Pathfinder Core Rulebook is somewhat vague on the requirements of resting and sleeping so the following is an extrapolation of existing rules combined with rules taken from d20srd.org combined with a bit of our own personal ideas. Use at your discretion.
The Pathfinder rules clearly indicate that the only types of creatures that do not sleep are constructs, oozes, plants and undead. Most other creature types must rest on a somewhat regular cycle. There are specific examples that do not, such as elementals. The exact required duration of that rest is unclear as well as the consequences of having less than the required amount of rest.
We think it is reasonable that most creatures must rest for approximately 1/3 of every day, which in most worlds translates to roughly 8 hours per day.
For most creatures resting means sleeping. In some worlds some races can gain the benefits of rest simply by sitting quietly maintaining an awareness of their surroundings, while in other worlds those races must sleep, which leaves them vulnerable to attack.
In any case, these are the actual benefits of rest, per the Pathfinder Core Rules.
Armor Note: A creature that rests or sleeps in medium or heavier armor gains the fatigued condition if they do not possess either the Endurance feat or some other class or race ability which allows them to sleep in such uncomfortable gear.
Fatigue from Lack of Sleep
Characters who do not get a full night's sleep may suffer the effects of fatigue. If a PC does not get at least 6 hours of sleep, she must make a DC 15 Fortitude save or be fatigued and take a –1 penalty on all other checks and saving throws against sleep effects. A second night without sleep requires another DC 15 Fortitude save. A failed save results in the character becoming exhausted and the penalties increasing to –2. A third failed save on the next night increases the penalties to –3
Thank you for digging that out. The "Fatigue from Lack of Sleep" is from the adventure path I mentioned above. However, the rest of what you cited is (although good) not RAW (I guess even the Fatigue from Lack of Sleep isn't RAW, as it isn't a part of the Core rules?).
Not being RAW is a serious issue. Without an entry in the CRB, my character build centered around not getting enough sleep and becoming Fatigued might not work in PFS.