How Anti-Sleep Alarms Function

We are all familiar with alarms that jolt us awake in the morning, but have you heard of alarms that help keep us alert while driving? Anti-sleep alarms do more than just annoy or startle—they can prevent accidents or worse by alerting drivers when they begin to doze off behind the wheel.

Anti-sleep alarms come in two varieties. One type is integrated directly into the car, utilizing sensors, cameras, and advanced technology to monitor the driver’s fatigue and take corrective action. The other type is a wearable device that fits over the ear and emits a sound when the driver begins to fall asleep. While in-car systems are newer, sophisticated features that can increase a car’s price significantly, the ear-worn alarms are affordable and widely available, typically costing $10 to $20 from brands like Nap Zapper, No Nap, and Doze Alert.

The names might sound amusing, but the importance of anti-sleep alarms is serious. A survey by the National Sleep Foundation found that 60 percent of Americans have driven while feeling drowsy, and 37 percent confess to falling asleep at the wheel in the past year. In fact, driving while tired can be deadly: According to the National Highway Traffic Safety Administration (NHTSA), drowsy driving leads to over 100,000 accidents and more than 1,500 fatalities annually [source: Fenton]. While the best approach is to get adequate rest or take a nap before driving, an anti-sleep alarm can be invaluable during a late-night drive.

Continue reading to learn how these devices can detect when you’re dozing and know when you're alert.

Detecting Driver Fatigue

Let's begin with the most basic anti-sleep alarm system: the over-the-ear device. This lightweight plastic gadget has a small arm that slips over one ear, similar to some telephone earpieces or portable headphones. Once placed on the ear, an internal sensor measures the angle from a perpendicular position. When the driver is looking straight ahead, the alarm measures the angle as zero degrees.

If you've ever nodded off on a subway or during a high school algebra class, you know that your head tends to droop forward as you fall asleep. You also know that you might stay asleep briefly before jerking awake. While this is merely annoying during a commute, it becomes hazardous when driving. The anti-sleep alarm detects any shift in the driver's head position: When the earpiece senses the angle increase from zero to, for example, 15 or 30 degrees, it triggers an alarm. Most manufacturers emphasize that the sound is loud and persistent enough to rouse the driver without being so abrupt that it causes panic or sudden wheel jerks.

You can easily adjust the threshold angle for triggering the alarm. If you can sleep with your head nearly upright, you can set the earpiece to trigger at a smaller angle. If the alarm goes off every time you nod along to music, set the triggering angle to 30 degrees or more.

While these alarms are effective at keeping drivers awake, some premium car manufacturers are incorporating sleep-monitoring sensors directly into their vehicles at the factory. A few notable systems include:

In-car systems can be pricey, especially those featuring in-dash cameras to monitor drivers, as opposed to utilizing pre-existing sensors. Keep reading to learn who can benefit from an anti-sleep alarm, regardless of the price tag.

Who Can Benefit from an Anti-Sleep Alarm?

Drivers are the obvious audience for anti-sleep alarms. Truckers with tight schedules often find themselves hauling cargo overnight. A simple earpiece alarm and a thermos of coffee might be enough to keep drivers alert without turning to medication. Even casual road-trippers, such as those heading out on a spring break adventure, could benefit from a sleep alarm.

Over-the-ear alarms aren't just for drivers. Students pulling all-nighters can skip the usual caffeine and instead use an earpiece alarm to stay awake. Night security guards, particularly those stationed at fixed posts or gatehouses, could also make use of this simple technology.

While these alarms can help keep tired drivers awake and alert enough to study, driving while drowsy is still dangerous. A sleep alarm, whether integrated into the car or worn on the ear, could give drivers a false sense of security. This potential risk led the Australian state of Victoria to prohibit the devices in 2007 until further safety tests were conducted.

Anti-sleep alarms can be helpful for drivers who prefer staying on the road rather than resting, but the most effective and safest solution for drowsy drivers is simply pulling over to take a quick nap.