swépnos

The noun *swépnos ("sleep, dream") derives from the verbal root *swep- ("to sleep") and is attested across the major branches with consistent semantics. Latin somnus ("sleep"), from *swep-nos with regular loss of *w after *s and assimilation of *pn > mn, yields somnolent, insomnia, somnambulism ("sleep-walking"), and the trademarked Sominex. The related soporific comes from a different but possibly related root. Greek hýpnos (ὕπνος, "sleep") shows the loss of initial *sw- > *hu- > hy-, the regular Greek treatment. The god Hypnos personifies sleep; his son Morpheus shapes dreams. Derivatives include hypnosis (coined by James Braid in 1843), hypnotic, and hypnotherapy. Sanskrit svápna ("sleep, dream") preserves the full form most transparently. The verbal root svápiti ("sleeps") and the derivative svapnáyate ("dreams") are productive in Vedic literature. The overlap between sleeping and dreaming in the Sanskrit semantic range reflects an ancient conceptual unity. Old English swefn ("dream, vision" — used in the compound swefn-racu, "dream-interpretation") preserves the form with the original *sw- cluster. The Modern English word sleep, however, derives from a different root (*slēb-), having replaced the inherited *swep- verb. The Gothic swefn and Old Norse svefn confirm the Germanic reconstruction. Old Church Slavonic sŭnŭ ("sleep, dream") and Lithuanian sãpnas continue the Balto-Slavic reflexes. Old Irish sūan ("sleep") and Welsh hun preserve the Celtic forms. The semantic range of *swépnos encompasses both the state of sleep and the experiences within it (dreams), a polysemy preserved in several branches. The differentiation of sleep and dream into separate lexical items is a later development in most IE languages.