Objective To determine through a daily process study whether alleged psychological and health behavior headache triggers reliably predict headache occurrence in children. Methods Twenty-five children aged 8–17 years with primary headaches reported on their expectancies for headache triggers and then used electronic diaries three times daily for 2 weeks to record headache occurrence, stressors, type and timing of food and drink intake, sleep and wake times, and sleep quality. Hypotheses pertaining to the association of presumed headache triggers and headache occurrence were evaluated using multilevel models. Results Only changes in stress level reliably preceded the occurrence of a new headache episode. Nights in which a child had less than his/her typical sleep quantity also tended to predict headache occurrence. Consumption of certain food and drink items was found to be protective. Conclusions Daily stressors seem to be a more reliable trigger of children’s headaches than diet or sleep factors.