Sleep

Sleep (SLP) is a derived statistic in Fallout: New Vegas in hardcore mode.

Characteristics
Sleep is a consequential statistic of the total time you've spent awake: the longer you are awake, the higher your sleep value becomes.

Beverages containing caffeine will reduce this value, as will having a break by taking a nap. Furthermore, sleeping in a bed you own or have rented will give you the Well Rested bonus for 12 hours.

As your sleep deprivation worsens your stats will be negatively impacted, starting with your Agility. Not sleeping for two weeks equals death.

Bugs
Sometimes the SLP meter on your Pip-Boy 3000 can get stuck on zero, and in fact will not display any number below the indication arrow. This is normally caused by travelling through canyon wreckage, which sets all hardcore meters to zero. During this time your character will not advance into sleep deprivation. This bug may be fixed by finding a bed and sleeping for any amount of time. After the player wakes, the gauge will display the number and resume its normal function.