Difficulty

Difficulty scoring on polyphasic.info is a system where scores go from 0 (trivial) to 5 (impossible):

0	Trivial: No adaptation is necessary, like Mono or BiX.
1	Easy: Adaptation doesn't involve extreme sleep deprivation and little impairment is expected as a result. Almost all people can adapt to these schedules.
2	Moderate: Adaptation involves more sleep deprivation and some impairment is expected. Still though, a vast majority can adapt and the willpower required is pretty easy to manage.
3	Hard: Adaptation involves significant sleep deprivation and impairment in everyday function is expected, but it is still possible with a large amount of willpower. Zombie-mode is not unlikely, but should be manageable. Not everyone can adapt to these schedules, but many still can.
4	Extreme: Adaptation involves a lot of sleep deprivation and immense amounts of will-power, but is physiologically possible, and can be reached with great alarm management and other accommodations, like not having much physical activity and being able to miss out on good mental functioning. A significant portion of people will not be able to adapt at all.
5	Impossible: Adaptation is physiologically impossible for the vast majority of people. When adaptation is possible, RSR can be assumed.