In this article data are presented that suggest that individual language learners may have different optimal times of the day for learning a foreign language. Learners were tested on vocabulary learning and retention at different times of the day. In addition, different components of language aptitude were tested. Two components of the language aptitude test show an effect of early risers (‘larks’) performing better in the morning than in the evening, and late risers (‘owls’) performing better in the evening than in the morning. It is argued that chronotype should be included as one of the individual differences components in second language development.