Multiple regression method of the indirect mediation model.25 a indicates the path from sleep durations (exposure) to mediator (i.e., inflammation, oxidative stress, and antioxidant. b indicates the path from mediator to outcome (i.e., metabolic syndrome (MetS), number of MetS components, and individual MetS components) controlling for the mediator. c indicates the path from exposure to outcome. c' indicates the path from exposure to outcome controlling for the mediator.