Overcoming Drowsiness by Inducing Cardiorespiratory Phase Synchronization

Drowsiness is one of the major factors leading to car accidents. Many automobile companies and institutions have been studying ways to monitor drowsiness and keep drivers awake. When drowsiness is detected during driving, audible sound, vibrations, or messages on a display are generally used to warn the driver to concentrate on driving or to take a rest. These methods help to prevent drowsiness-related crashes to some extent, but for greater safety, methods need to be developed to physiologically overcome drowsiness. The key to overcoming drowsiness is to keep the body constantly supplied with oxygen. We focused on cardiorespiratory phase synchronization (CRPS) to recover from oxygen desaturation during drowsiness. This study found it possible to induce CRPS by paced breathing (PB) using pulse sound, which synchronized with heartbeats. The experiment results showed SpO2 measured from forehead increased during this PB. The increase in SpO2 was larger than that of yawns, deep breathing, or a period of drowsiness spontaneously reduced. In conclusion, inducing CRPS by PB using pulse sound synchronized with the heartbeat has the potential to reduce drowsiness physiologically.