Road trips are a summer staple, as essential to the warm-weather months as sunburns or cannonballs in the deep end. And all memorable journeys are bound by a few important rules. Mine? Snacks are a must, the driver’s in charge of the radio and — most importantly — no sleeping while I’m at the wheel. If I’m awake and driving, then you’re awake and passenger-ing. Plain and simple.
Not that it’s all that easy to fall asleep in a moving car, anyway. Thanks to rumble strips, stop lights and hairpin turns, sleeping on the road can be as hard as sleeping on a plane. The strange thing, however, is that while there's plenty of advice on how to sleep while crammed in coach, there’s not much on the ins and outs of catching shuteye in the car. For the sake of roadtrippers everywhere, I reached out to several sleep professionals to secure some answers and discovered that dozing on the road comes down to two things: safety and seat angle.
My rule about “no sleeping while I’m driving” mostly exists to protect me from being bored and lonely, or needing to lower the radio (roaaaad trrrripp!). But Rafael Pelayo, a professor at Stanford University’s Center for Sleep Sciences and Medicine, points out an additional safety aspect. When passengers are sleeping in the car — especially on long trips — the driver may be more likely to nod off as well.
“What’ll happen is while you’re sleeping the driver will try to be considerate and keep everything quiet and calm...keep the music down to help you sleep,” he said. “That’ll make the other person sleepy also.”
According to Pelayo, it's only safe for passengers to sleep in a car when at least three people are present. In that scenario, at least one person can stay up and keep the driver company while the other sleeps.
Now that we’ve gotten that out of the way, there may be a few factors that can heavily influence a passenger’s ability to fall asleep.
First off, Pelayo says that the safest way for a passenger to nod off is in the backseat, so a second passenger can stay awake up front with the driver. In most cases, this means that the passenger will either have to sleep sitting upright or lying across the seat. The former is uncomfortable, and the latter, while more conducive to shuteye, is less safe in the case of an accident. So that’s not really ideal.
If the backseat happens to recline, however, then you’re in luck: Past research (admittedly from several decades ago and focusing on a small sample size) suggested that adequate sleep can be achieved while sitting up if the chair reclines at an angle of 40 degrees or greater. The same study found that sleeping while sitting nearly straight up, on the other hand, resulted in poor sleep quality compared to sleeping while lying down. Although, more research is needed to draw any definitive conclusions. (For the record, several years ago Slate asked Michael Decker of the American Academy of Sleep Medicine whether it was possible to get a good rest sleeping while sitting up and concluded that it is — but also pointed to the same research suggesting that 40 degrees is the ideal reclining angle.)
In general, then, it seems that having to sit up without an adequate reclining angle poses the biggest hurdle to travelers trying to get some rest, whether it’s in a car, plane or other mode of transport. This really is no surprise, especially if you consider what happens to the body during sleep.
During slow wave sleep, our muscles become relaxed. Ever nod off at your desk during work or school? Well, then you’ve likely felt yourself slip or or slump forward, waking up as a result. Unless you’re lying down or reclining in a stable position, you’ll likely wake yourself up as soon as you start to drift. Not ideal for erect slumber, in-car or otherwise.
General common sense comes into play with car Zzzs, too. Pelayo suggests planning ahead if you want to sleep while traveling and knowing what time you want to rest and for how long. It’s best not to drink caffeine within six-ish hours of the time you'd like to sleep, and Pelayo also recommends avoiding over-the-counter sleep medication, which he says may not last long enough to be effective. And it’s usually easier to fall asleep in a cool environment, so blasting the air conditioning may help as well.
Of course, the conditions that are most conducive to a passenger's rest may leave the driver feeling sleepy too, so there’s a risk factor no matter what, Pelayo cautions. And this makes it all the more important to make sure at least one person is awake and engaging the driver in conversation.
So, given the right conditions, it is possible for passengers to get quality rest. But it's not best practice, as far as safety or summer vibes are concerned.