The gentle vibration and background noise of a moving car induces sleep for many people. This may be partly because it replicates what we feel and hear in the womb.
“For some people, being a passenger in a car is an opportunity to switch off,” explains Dr Guy Meadows, clinical director of The Sleep School in London. “Having someone else driving gives them a sense that someone else is in charge, so they can relax. Some of us are also able to switch off more than others, so light and noise have less impact. But if you’re an anxious passenger, the opposite is true. For these people, any bump, braking or acceleration merits attention – they also feel they need to watch out for the driver.”
This is why young children fall asleep in cars – because they’re trusting of the driver as well as living much more in the moment instead of worrying about things. Cars are also uncomfortable to sleep in. We sleep best lying down because our muscles can relax better, adds Dr Meadows.