<p>Poor sleep hygiene can have a negative impact on the effectiveness of obesity treatment. The aim of this study was to explore associations between sleep patterns, food/beverage consumption, and maladaptive eating behaviors of Portuguese children/adolescents under treatment for overweight/obesity and their caregivers (N = 110). Bedtime irregularity between weekdays/weekends was associated with higher fast food intake. Sleep duration, bedtime hour, and sleep regularity of children/adolescents between weekdays and weekends were positively associated with their caregivers’ sleep patterns and problematic eating behaviors. An insufficient number of hours of sleep, late bedtime hours, irregular sleep patterns between weekdays, and weekends seem to be associated with unhealthy eating habits and negative changes in eating behavior.</p>