Want to know one of the biggest causes of preventable car accidents that very few people know about?

It’s sleep deprivation.

Most lawyers look at the car crash itself, or the few seconds leading up to the crash. But what a tired person does before getting in the car can matter almost as much as what he or she does when behind the wheel.

If you aren’t getting enough sleep beforehand, your car crash risk increases exponentially — up to nearly 12 times higher. 1 in 3 drivers are not getting the proper amount of sleep — raising their car crash risk and causing them to be as ‘substantially impaired’ as driving drunk.

Not enough shut-eye raises your car crash risk up to — and past — drunk-driving levels of impairment

According to the AAA Foundation for Traffic Safety, not putting in the minimum recommended 7 hours of sleep can raise your car crash risk significantly. Its “sleep deprivation” report finds that getting just 5 to 6 hours of sleep in a 24-hour period doubles your risk.

Keep the Sandman at bay, and your risk gets even worse: just getting in 4-5 hours of sleep more than quadruples your chances of getting in a wreck.. This is a figure the National Highway Traffic Safety Administration associates with driving over the legal limit for alcohol, and what the National Sleep Foundation says makes a driver “substantially impaired.”

Less than 4 hours of sleep? Shockingly, you are now nearly 12 times more likely to be involved in a car crash.

Even worse, the Centers for Disease Control and Prevention says that a staggering 35% of U.S. drivers sleep less than the recommended 7 hours daily.

That’s 1 in 3 drivers. Could you be one of them?

Symptoms aren’t always obvious

Typical signs that you're drowsy include having trouble keeping your eyes open, missing exits, drifting from lane to lane, hitting roadside rumble strips, and not remembering the last few miles driven.

But the AAA-FTS’ studies found that more than half of drivers involved in fatigue-related crashes experienced no such symptoms before falling asleep behind the wheel.

The solution, then, is to always try to get at least 7 hours of sleep, instead of relying on your

body to provide warning signs of fatigue when it’s too late.

If road time can’t be avoided after a bad couple nights of sleep

Sometimes we can’t avoid getting behind the wheel, even when our sleep has been compromised and our risk of being involved in a car crash has shot upwards.

To remain alert and avoid drowsiness:

• Travel at times when you are normally awake, and stay overnight rather than driving straight through.
• Schedule a break every two hours or every 100 miles.
• Stop driving if you become sleepy. Fatigue impacts reaction time, judgment and vision, causing people who are very sleepy to behave in similar ways to those who are drunk.
• Don’t work all day and then drive all night.
• Travel with an awake passenger who can take the wheel when you’re feeling fatigued.
• Make sure your medications won’t make you drowsy. Tiger Woods’ arrest is a high-profile example of the effects of drugged driving, which is now a bigger threat than drunk driving.

Banish sleeplessness from your schedule

We live in a world of never-ending information on our smartphones and tablets. The National Sleep Foundation reports that smartphones emit blue light, which is a type of light that the brain interprets as daylight. That means when looking at a smartphone right before bed, your body’s melatonin — the hormone that helps with sleep timing and kicks in when your normal bedtime approaches — is thwarted, because your brain is thinking it’s not actually 11 p.m. yet.

Some of the Mayo Clinic’s suggestions for better sleep include:

• Stick to a schedule: Your bedtime and wakeup time should be consistent so that your body’s sleep-wake cycle is reinforced.
• Be cautious with eats and drinks: Avoid heavy or large meals within a couple of hours of bedtime, as the discomfort could keep you up. Caffeine can take hours to wear off and can wreak havoc on quality sleep. And while alcohol might make you feel sleepy, it can disrupt sleep later in the night.
• Limit daytime naps: Long daytime naps can interfere with nighttime sleep. If you must nap, limit yourself to up to 30 minutes and avoid doing so late in the day.
• Manage your worries: Try to resolve your worries or concerns before bedtime. Jot down what’s on your mind and then set it aside for tomorrow.
• Make your environment a restful one: Your room should be cool, dark and quiet. Calming activities before bedtime, such as taking a bath or using relaxation techniques, also help.