Sleep, Hansen's disease and the immune system--a not so harmonic triad.

Hansen's disease is one of the oldest skin diseases in the world characterized by a spectrum of clinical manifestations that are associated with stigmatization and poor quality of life. It is also considered a model disease for investigating the human immune system because of its association with immune reactions, which are thought to be a reflection of the host's immunological response, promoting intense cellular activity or humoral secretion. This relationship between the cellular and microbial components of skin and their regulation by local immune responses may be modulated by a currently neglected behavior: sleep. Recent studies have demonstrated that sleep deprivation may aggravate the progression of chronic dermatological diseases, which in turn can lead to a non-restorative sleep pattern. Indeed, sleep is essential for immune and skin integrity. Thus, we propose here a hypothesis linking Hansen's disease, sleep and immunity in a bidirectional relationship. Hansen's disease patients may demonstrate a worse sleep quality than the general population through the modulation of immunological environment; and sleep restriction, a hallmark of modern society, being a possible predictor of the disease progression.