Fish, like humans, require sleep for recovery, and a recent study published in Nature Communications reveals that their sleep patterns are surprisingly similar to ours. While most fish are diurnal and sleep primarily at night, they lack eyelids, making them unable to close their eyes. However, light can still disrupt their sleep. Researchers tracked the eye movements of zebrafish, identifying four sleep substates akin to human sleep stages. The first substate is the deepest, characterized by a fixed stare, followed by lighter stages where the fish exhibit eye twitching and lateral movements. Interestingly, zebrafish can compensate for sleep deprivation by sleeping longer the following night. Even short naps during the day can significantly suppress brain activity, indicating that fish experience deep rest. This study sheds light on the complexity of sleep in fish, suggesting that their sleep structure is more intricate than previously understood, and highlights the importance of sleep across species.