A Sleeper is a Virtual World participant that cannot leave the V-World. Sleepers are rumored to exist; there are no verifiable cases of actual sleepers. Sleepers are named such since they supposedly have fallen asleep while wearing their holoband. More intense conditions of unconsciousness, such as a comatose state, may also manifest as sleeper participants.
Being a sleeper is apparently dangerous, perhaps since the condition of being virtually awake while wearing a holoband inhibits the body's ability to awaken itself in the real world; one may require external stimulation, such as a partner shaking the victim.
The holoband has a safety feature that automatically disconnects the participant. This may be a function of time, or perhaps it detects brainwave anomolies. ("There is Another Sky")