This study investigated the associations between various factors anecdotally reported to trigger headache and migraine. Headache symptoms and headache triggers were assessed using a questionnaire given to 180 volunteers. Two groups were identified, those who fulfilled the International Headache Society's criteria for migraine, and those who did not. Associations between reported headache triggers were explored using a principal components analysis, which grouped common headache triggers into four components: visual stimuli, food, alcohol, and stress/tiredness. The visual stimuli cited as triggers included flickering light, repetitive patterns (stripes), sunshine, patterns of light and shade, glare, bright reflections, computers, TV and the cinema. A separate analysis on the data from the migraine group produced the same four components together with a fifth, interpreted as a non-visual sensory trigger (noise and smell). The results demonstrate that visual stimuli are commonly reported as headache triggers. Those involved in the design of the visual environment could improve the quality of life of many by avoiding environmental factors, particularly visual factors, which can trigger headache and migraine.