Short and long nightly sleep durations are associated with anxiety and depression symptoms among adolescents. However, studies have not used recommended hours of nightly sleep or focused on sleep patterns across weekdays and weekends in examining links with anxiety and depression symptoms. The present study included 709 adolescents in Grade 11 (402 females; 307 males) who self-reported hours of sleep on weeknights and weekends and anxiety and depression symptoms. Using the recommended 8–10 h to define average nightly sleep for adolescents, sleep patterns across weekdays and weekends were categorised into seven classes: short stable, short increasing, average decreasing, average stable, average increasing, long decreasing, and long stable. Relative to average stable sleepers, short stable, short increasing, and long stable sleepers had significantly higher anxiety and depression. Adolescents require 8–10 h of sleep on weeknights, regardless of weekends, for optimal emotional wellbeing.