Effects of night shifts in bipolar disorders and extreme morningness

Abstract

Night work and shift work scenarios are increasing in modern society. Instability in the sleep-wake rhythm is an important risk factor for triggering episodes of bipolar disorder. Extreme chronotype has negative effects on shift work ("shift-worker syndrome"). Effects of night or shift work on patients with bipolar disorder and extreme chronotype are not well understood. A patient with bipolar II disorder and extreme morning type followed a stable work schedule for a significant period of time, maintaining a stable mood. After changing to a night-shift schedule, depressive symptoms developed. When the night-shift schedule was stopped, her mental state normalised. This case highlights the possibility of a sensitizing role of chronotype in triggering episodes of bipolar disorder after the sleep-wake rhythm has been disrupted by night work or shift work. The evaluation of a person's capability to perform night work or shift work should take into account psychiatric disorders and chronotype as well as physical conditions.