Insomnia, biological clock, and the bedtime decision: an economic perspective.

While insomnia can be a symptom of numerous mental and physical illnesses, it is frequently diagnosed as a sleep disorder in its own right, caused mainly by stressful life events or by non-synchronization of individuals' biological sleep-wake cycle with the one they choose to practice. Because of irregular work schedules, late-night entertainment, or rapid crossing of several time zones, individuals might retire to bed earlier or later than their biological bedtime, experiencing difficulties in falling asleep. The present paper develops a simple economic model of the bedtime decision, viewing the individual as a rational decision-maker who determines her insomnia level through consciously weighing the cost and benefit of deviating from her biological bedtime. The model is then used to examine the individual's response to stress, yielding a prediction which is consistent with observed behavior, although not with sleep therapists' recommendations. Finally, the model is applied to the case of transmeridian flights, explaining jet lag as a rational adjustment to a misalignment between the individual's slow-to-adapt internal clock and her external environment.