With 6-10 regular hours of sleep a day, you will not get very tired until the same time the next day. After this point you will begin to feel tired. This has no significant effects, but it is a sign that you should get some rest.
After 24 hours awake: You are less inhibited, less capable of carrying out tasks, and more prone to mood swings. All of your disciplines suffer a -1 penalty. At this point, the GM should roll 2d12 to determine how many hours will pass before the player must next make a d10 roll to stay awake. If the player rolls 5 or lower, they fall asleep unless engaged in a strenuous task.
After 36 hours awake: You suffer memory loss here and there. Mood swings become more frequent. The discipline penalty increases to -2.
After 48 hours awake: You begin having momentary blackouts. These microsleeps are disorienting. The discipline penalty increases to -3
After 72 hours awake: you begin experiencing hallucinations. Simple tasks now require discipline checks. The discipline penalty increases to -4
After 96 hours awake: you have few periods of consciousness. The discipline penalty increases to -5.
After 120 hours awake: you fall asleep without resistance.