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Heart rate (HR) decreases and heart rate variability (HRV) increases during sleeping. However it is not investigated how they change during falling asleep while driving a car. This is basic study for developing heart rate monitoring system inside a car for preventing falling asleep while driving a car.
Healthy volunteers are monitored with 24hour holter monitoring systems for HR and HRV starting 8AM to 11AM for 24hours. They are instructed to push the button if they feel sleepy or arrhythmia while driving a car. If the volunteers cannot help sleeping while driving a car, they are ought to change seat with person at passenger seat and feel free to sleeping at the passenger’s seat while sleeping.
Four healthy volunteers who are planning to drive a long journey were enrolled. They are all male and 40.2 years old of mean age. Their mean driving time is 5 hours majorly at express way. They felt sleepy 2±1 hours after starting driving and the mean duration of falling asleep time is 17±4minutes. While driving their mean heart rate was 86±5 beats/min and this decreases by 15±5% while they feel sleepy. HRV increased by 10% 0.16Hz to 0.18Hz while they are falling asleep. One volunteer change the seat from driver’s to passengers when he cannot help sleeping, the HR and HRV changed much more from 89 beats/min to 65 beats/min and from 0.09 Hz to 0.23Hz. When they slept at night the HR decreased from 86 beats/min to 75 beats/min by 12.8% and HRV increased from 0.1Hz to 0.25Hz.
This pilot study the first time demonstrated the HR decreased and HRV increased while feeling sleepy while driving a car. HR decreased significantly when the driver slept at the passenger’s seat at the car as well as sleeping at night.