Objective: The purpose of the present study was to examine the contribution of sleep related factors, including previous night sleep, past experience with sleep loss and current energy, to objective effort and the subjective experience of effort. Method: 187 non-sleep-deprived college students from Baruch College completed a 1- hour computer assessment which included eight tasks: general sleep questionnaire, sleep diary, Stanford Sleepiness Scale, Profile of Mood States, reaction time task, Math Effort Task, and non-academic task selection question. Results: Principal components analysis was used to identify 8 factors and form composite variables. Those factors were entered into hierarchical regressions to predict effort. Objective effort, but not subjectively rated effort, could be predicted and was most related to actual sleep and perceived energy. 10% of the variance of objective effort was accounted for by actual sleep, perceived energy, reaction time and interactions among these components. Conclusions: Under non-sleep-deprived sleep conditions, objectively measured effort is affected by previous night’s sleep and perceived energy. Objectively measured and subjectively rated effort, however, derive from different sources. The potential danger of reduced energy caused by even minimal sleep loss is that less effort may be applied in situations where maximal effort is expected or needed. Future research may clarify the mechanisms by which sleep affects effort and the effects of accumulated sleep loss on effort.