Sleep debt loan sharks may use schemes such as spontaneous microsleep, low cognitive capabilities, and (if the sleep debt is extraordinarily high) auditory and visual hallucinations, in order to make a person pay off his or her sleep debt.
As with regular loan sharks, sleep debt loan sharks can be staved off temporarily. In this case, it is through the use of psychostimulants, such as caffeine, amphetamines, ecstasy, cocaine, etc.
Godfrey: Nah man, them sleep debt loan sharks be keepin' me down. Gotta get me some sleep n' sh*t befo' I get real f*cked up.
Edwin: Yo man, two words: Coffee, biotch!