How to Sleep in Your Car Safely (Road Trips, Rest Stops, Overnights)

To sleep in your car safely, pull over somewhere legal and well lit, turn off the engine, lock the doors, crack a window for fresh air, and recline or move to the back seat. Never run the engine in a garage or other enclosed space, because carbon monoxide can kill you while you sleep. For a quick roadside rest, a 20-minute nap is usually the sweet spot. For a full night, plan for temperature, privacy and a steady supply of fresh air.

If you're drowsy behind the wheel right now, stop at the next safe place. That's the most important part of this guide.

When should you pull over and sleep?

As soon as you notice drowsiness, not when you're about to nod off. Warning signs include heavy eyelids, frequent yawning, drifting out of your lane, missing an exit, or not remembering the last few miles.

The risk climbs fast with short sleep. A study of nearly 7,000 drivers in US crashes found that, compared with drivers who'd slept 7 to 9 hours:

Being awake for a long stretch can impair you about as much as alcohol does. The how long can you go without sleep guide has the numbers. Turning up the radio or opening a window isn't a fix; sleep is.

How to take a 20-minute nap in your car

A 10 to 20 minute nap is long enough to lift alertness and short enough to avoid waking up groggy. Here's how to do it on a drive.

1. Pull off the road completely. A rest area, a well-lit gas station or a parking lot beats a highway shoulder.
2. Turn off the engine and lock the doors.
3. Recline the seat or move to the passenger side so the steering wheel isn't in the way.
4. Set an alarm. If you usually take about 15 minutes to drift off, lying down at 2:00 PM means an alarm at 2:35 PM for a 20-minute nap. The nap calculator works it out for your own timing.
5. Give yourself 10 to 15 minutes after waking before you drive. Walk around, get some air, let the fog clear.

Avoid napping 30 to 60 minutes if you have to drive right after. That length tends to end in deep sleep, which is when you wake up feeling worst. If you're on a work break, the guide to napping at work covers the coffee-nap trick for drivers.

How to sleep in your car overnight

A full night in the car takes more planning than a nap: a legal spot, air, temperature and some comfort. Use this checklist.

Where to park

• Choose a place where overnight parking is allowed. Rules differ by state, city and property owner, so check posted signs and ask staff if you're on private property. Some rest areas have time limits.
• Pick somewhere well lit with other people around, but away from the busiest traffic lanes.
• Park so you can drive straight out without reversing, in case you need to leave quickly.
• Tell someone where you are if you're traveling alone.

Air and carbon monoxide

Carbon monoxide is odorless and colorless, and the CDC warns that people who are asleep can die from it before they have any symptoms.

• Never run the engine in a garage or any enclosed space, even with the door open.
• Turn the engine off to sleep whenever you can.
• Crack a window or two about a finger's width for fresh air and to cut condensation.
• In snow, keep the exhaust pipe clear. If you're stranded and must run the engine for heat, the National Weather Service advises running it about 10 minutes each hour, with a window open a little and the tailpipe clear of snow.

Temperature

• Cold: Dress in layers, add a hat and socks, and use a sleeping bag or thick blankets rather than relying on the heater. Put a blanket under you as well as over you; the seat pulls heat away.
• Heat: A parked car can get dangerously hot. Don't try to sleep in a closed car in hot weather. Park in shade, open windows wider if it's safe, and use window shades. If it's too hot to sleep safely, find somewhere else.

Comfort and privacy

• Lay as flat as you can. Fold down the back seats if your car allows it, or recline the passenger seat fully.
• Use a pillow and something to fill the gaps, like a rolled jacket under your lower back.
• Cover the windows with sunshades or towels for privacy and to block streetlights and early sun. An eye mask helps too.
• Earplugs dull traffic noise, but keep your alarm loud enough to hear.
• Keep keys, phone and a flashlight within reach, and charge your phone before you settle in.

How long should you sleep in your car before driving?

A 20-minute nap buys a short boost, not a full reset. If you've been up most of the night or slept very little, a single nap won't make long-distance driving safe. A full 90-minute cycle or a proper night's sleep is better before a long stretch; see is a 90-minute nap too long for the trade-offs.

If you keep needing to pull over on every trip, look at your nights. Use the sleep calculator to plan a bedtime that gives you enough sleep before a long drive, and check the signs you're sleep deprived. If you nod off easily during the day despite enough sleep, or you snore loudly with pauses in your breathing, see a doctor.