ATLANTA — Find yourself yawning a lot? Do you need that third or fourth cup of coffee to make it through the afternoon at work? Such signs of sleepiness may be a red flag of a serious sleep deficit ...

Yawning reverses cerebrospinal fluid flow, boosts brain blood surge, and may aid cooling and waste movement, challenging the idea that it signals boredom alone.

(CNN) — Find yourself yawning a lot? Do you need that third or fourth cup of coffee to make it through the afternoon at work? Such signs of sleepiness may be a red flag of a serious sleep deficit that ...