Mechanik’s Union

When quaffed by the character, the character will feel as if he or she had had 2d4 hours of rest. This will automatically move an exhausted character into fatigued, and a double dose (4d4 hours of rest) will move fatigued character into rested.

The effects last 2d10 hours, then the crash hits. The body stress of all this will result in 2 points of Con damage, plus 1 con point per 2 hours of duration. The con damage will never lower a character’s constitution lower than 1

From the SRD:

Exhausted
An exhausted character moves at half speed and takes a -6 penalty to Strength and Dexterity. After 1 hour of complete rest, an exhausted character becomes fatigued. A fatigued character becomes exhausted by doing something else that would normally cause fatigue.

Fatigued
A fatigued character can neither run nor charge and takes a -2 penalty to Strength and Dexterity. Doing anything that would normally cause fatigue causes the fatigued character to become exhausted. After 8 hours of complete rest, fatigued characters are no longer fatigued.