A phototherapy device suitable for shining light on a vehicle driver (3) in order to suppress melatonin production and increase wakefulness, having at least one light fixture (1) located in the region of the head of the driver (3), is improved in terms of its freedom front glare, with undiminished effectiveness, in that the light fixture (1) is embodied to emit essentially nondirectional diffuse light (7) and is located outside the field of view of the driver (3), or at least in the peripheral region of his field of view.