To characterize the insomnia suffered by Franz Kafka (1883-1924), one of the most important literary figures of the 20th century.We read Kafka's diaries and private correspondence to his fiancée, friends, editors and relatives looking for references to his insomnia.We found 292 references to insomnia indicating that Kafka suffered from chronic insomnia disorder that originated from and was maintained by the following predisposing and precipitating factors: (1) a complex personality predisposing to an increased arousal level, (2) intrusive thoughts and ruminations at bedtime, (3) excessive worrying about sleep loss and its daytime consequences, and (4) an extraordinary intolerance to noise. Since he could not sleep at night and felt the necessity to compose his literary works in an absolutely quiet environment, Kafka deliberately changed his sleep-wake schedule so he could write at night and nap in the afternoon. These maladaptive sleep habits perpetuated his insomnia and led to chronic sleep deprivation resulting in fatigue, lack of concentration and sleep-related auditory, tactile and visual hallucinations. Kafka sought help in alternative medicine however this was ineffective in improving his insomnia.Kafka suffered from chronic insomnia disorder and had inadequate sleep hygiene resulting in chronic sleep deprivation. These sleep problems impaired Kafka's quality of life.