The phrase "vicious cycle" in paragraph 7 means... 1. ...a course of everyday events. 2. ...a large amount of extra work. 3. ...a sudden wave of tiredness. 4. ...a repetitive cycle of poor sleep consequences.

The phrase "vicious cycle" in paragraph 7 means... 1.  ...a course of everyday events. 2.  ...a large amount of extra work. 3.  ...a sudden wave of tiredness. 4.  ...a repetitive cycle of poor sleep consequences.