Crystal Math a.k.a. Crank

"It's time to get some sleep when:

• You're out of crank
• Your face is bouncing off the table
• Your veins have completely disappeared beneath pasty goose flesh
• Your shoes don't fit anymore
• 24 simultaneous projects have stalled for lack of floor space suddenly
• everyone is a cop
• You've just set yourself on fire, again
• You're nodding out...
  • into glassware
  • 15 minutes after shooting a 1/4g
  • at stoplights
  • in mid-sentence
  • in mid-shot
  • in mid-fuck"

(Speed Phreak)
Brilliant! My heydays are already over. I wish somebody would have told me this back in the days ;-) Kids: Don't even start.