Insomniac/ɪnˈsɑːmniæk/ Definition 1 of 2Pro Tip 1/3Health Context Used to express concern for someone's well-being when discussing sleep issues. I'm worried about Lisa; she's a real insomniac these days. Pro Tip 2/3Not Literal 'Insomniac' is sometimes used figuratively to describe temporary sleeplessness. I'm such an insomniac during exam week. Pro Tip 3/3Intensity May imply severity; 'chronic insomniac' suggests long-term sleeplessness. My uncle has been a chronic insomniac for years.