Somnolence (or "drowsiness")'s a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods (c.f. hypersomnia). It's two distinct meanings, referring both to the usual state preceding falling asleep, and the chronic condition referring to being in that state independent of a circadian rhythm. The disorder characterized by the latter condition's most commonly associated with the use of prescription medications such as mirtazapine or zolpidem. It's considered a lesser… (More on Sleepiness)