This chapter focuses on formulating an integrated position on sleepiness in long sleepers. It reviews studies conducted through a pathology lens, where long sleepers frequently include individuals in poor physical or psychological health, who are often older and experience poor nocturnal sleep quality, including insomnia. Most epidemiological studies investigating sleepiness and the behavioral and psychological characteristics of long sleepers have examined the extremes of sleep duration relative to each other. Existing empirically supported models of sleep regulation postulate that duration and timing of sleep are regulated by an interaction between a circadian pacemaker, which programs daily cycles in sleep propensity, and a sleep homeostat, which tracks increases in sleep pressure. Investigations conducted outside the U-shaped pathology lens have also found that long sleepers who do not have insomnia are no sleepier than midrange sleepers.