Although previous studies have shown that sleep can inspire insight, it is still unclear whether meditation can promote insight. Meditation differs from other types of passive rest such as relaxation and sleep because it requires full consciousness and mindfulness of targets such as one's breathing. Forty-eight university students without meditation experience were recruited to learn a simple meditation technique. They were given a list of 10 insight problems to solve (the pre-test session). In this study, we focused on the unsolved problems and examined if they could be successfully solved after a 20 min rest interval with or without meditation. Results showed that relative to the control group that listened to Chinese or English words and made a language judgment, the groups who learned meditation successfully solved significantly more failed problems from the pre-test session, providing direct evidence for the role of meditation in promoting insight. Further analysis showed that maintaining a mindful and alert state during meditation (raising a hand to report every 10 deep breaths compared to every 100 deep breaths) resulted in more insight regarding the failed items from the pre-test session. This implies that it was watchfulness in meditation, rather than relaxation, that actually contributed to insight. Consistently, in the meditation session or control task, the percentage of alpha waves-a brain index of mental relaxation-was negatively correlated with insight. These results suggest a meditation-based insight-promoting mechanism different from that involved in passive rest such as relaxation and sleep.