soporific

sop•o•rif•ic (sop-uh-RIF-ik)

Definition: 
adj
1. causing or tending to cause sleep
2. pertaining to or characterized by sleep or sleepiness; sleepy; drowsy

noun
something that causes sleep, as a medicine or drug

soporifically adverb
Origin:
1665 adj, 1727 noun; from Fr. soporifique, formed in French from L. sopor (gen. soporis) "deep sleep," from a causative form of the PIE base *swep- "to sleep"

Related:
Synonyms: anesthetic, quietening, sedative, slumberous, somniferous, somnolent, soothing, tranquilizing, hypnotic, soporiferous

Sentence Examples:
• Time, which beautifies unlovely things, begins to cast its glamour over the old Italian régimes. It is forgotten how low the Italian race had fallen under puny autocrats whose influence was soporific when not vicious. -Cavour, Countess Evelyn Martinengo-Cesaresco

• But the Magnolia was fragrant, like its namesake, with mint and herbal odors, cool with sprinkled floors, and sparkling with broken ice on its counters, like dewdrops on white, unfolded petals—and slightly soporific with the subdued murmur of droning loungers, who were heavy with its sweets.  -Colonel Starbottle's Client, Bret Harte

• An author must ever wish to discover a hapless member of the Public who, never yet having read a word of his writing, would submit to the ordeal if reading him right through from beginning to end. Probably the effect could only be judged through an autopsy, but in the remote case of survival, it would interest one so profoundly to see the differences, if any, produced in that reader's character or outlook over life. This, however, is a consummation which will remain devoutly to be wished, for there is a limit to human complaisance. One will never know the exact measure of one's infecting power; or whether, indeed, one is not just a long soporific.  -Villa Rubein, John Galsworthy

The Storyline
The effect on Anna of emptying this long contained rage was soporific and upon completion she slumped into her chair before a stunned father and mortified mother-in-law.

Sources: Dictionary.com, Online Etymology

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