One of the main causes for Lark not recording sleep time correctly is that Lark passively computes your sleep using your smart phone's motion sensors. Specifically, your sleep time is computed as the time between the last time you touch your phone before sleeping and the first time you use your phone after waking up. If you check your phone in the middle of the night or if you sleep with your phone nearby, Lark may detect this motion and incorrectly record your sleep. We apologize for any inconvenience this may cause you. To edit your sleep data in your Lark application, please check out this article.