Requiem for a Dream (2000)

Ellen Burstyn's Oscar-nominated performance is the reason to brave it. She plays Sara, a lonely Brooklyn widow who is told she might appear on her favourite game show and starts on diet pills to fit back into an old red dress, while her son and his friends deal heroin to fund their plans. An average 100-minute film has 600 to 700 cuts; Darren Aronofsky's has more than 2,000, many in the stuttering bursts he fires off whenever someone gets high. It is relentlessly bleak, and the distributor released it unrated rather than cut it for the R rating.