An insomniac is a person who cannot sleep easily, or cannot sleep well, as a pattern — someone who lives with insomnia. It is also a describing word: insomniac nights, an insomniac patient. Though actually, people sometimes say it with a small smile, as if it were a personality: “I’m an insomniac; I get my best ideas at two in the morning.” That can be light talk. The heavier meaning is someone who really suffers, week after week. The word is ordinary, a little more colourful than “a person who can’t sleep.” Do not mix the person with the problem: you have insomnia; you are an insomniac.

失眠者、失眠的人（也可當形容詞：失眠的）