Sleep

SLP, or Sleep, is a derived statistic in Fallout: New Vegas in Hardcore Mode.

Characteristics
Sleep is a measurement of the raw time you've spent awake. Beverages containing a bit of caffeine will help keep you awake longer, as will stopping your adventure and taking a nap. Not sleeping for two weeks will cause you to die.

Stages of Sleep Deprivation
Minor Sleep Deprivation(200-399): Agility -1

Advanced Sleep Deprivation(400-599): Intelligence -1, Agility -2

Critical Sleep Deprivation(600-799): Endurance -1, Intelligence -2, Agility -3

Deadly Sleep Deprivation(800-999): Endurance -2, Intelligence -2, Agility -3