Fatigue is a 'reduction in physical and/or mental capacity as the result of physical, mental, or emotional exertion which may impair nearly all physical abilities including: strength, speed, reaction time, coordination, decision making or balance'. The literature is quite clear on the debilitating effect of fatigue on (different aspects of) performance. Fatigue behaviours that are often mentioned when fatigue was considered to be a cause of collisions and groundings are 'activation problems', meaning decreased vigilance and decreased alertness, and 'perception (and sensory input) limitations', meaning a reliance on visual inputs, decreased attention to peripheral stimuli, uncertainty of the observations, and decreased communication. Particularly these fatigue behaviours are often found in reports from collisions and groundings occurring between 00:00 to 04:00 hours, but are also quite prevalent in collisions and groundings occurring between 20:00 to 00:00 hours. Because several organisations are already active in increasing the monitoring of causes, behaviours and consequences of fatigue, this option was not selected to be assessed on its consequences for the shipping industry and maritime.