Accurate time synchronization is crucial for distributed physiological monitoring systems, ensuring precise temporal alignment of data across multiple wearable devices. While Bluetooth Low Energy (BLE) is widely used in wearable devices due to its low power consumption and cost-effectiveness, existing BLE time synchronization methods often rely on external hardware or specific platforms, limiting their universality. This paper first analyzes the limitations of traditional one-way message exchange-based time synchronization methods in BLE, particularly the random access delay introduced by the connection event mechanism, which significantly degrades synchronization accuracy. To address this issue, we propose an application-layer time synchronization method based on message reception events. The method achieves high-precision synchronization with an accuracy of 20 μs by transforming the access delay from a random variable into a relatively stable one, and it also supports periodic synchronization to mitigate the cumulative effects of clock drift, making it suitable for wearable physiological monitoring applications.