Type the word "sleep" into the Apple App store search bar, and hundreds of smartphone and computer applications will appear.
There are sleep trackers, smart alarm clocks, and white noise generators — all portable technologies designed specifically to do something that many of us have a surprisingly hard time with: sleeping.
About 70 million people in the US suffer from sleep-related problems. Of those, about 60% have a chronic disorder.
Nearly two thirds of people in the US own a smartphone. If you're one of the millions who suffer from restless nights, it may be tempting to download one of those sleep tracking applications to sniff out the root of the problem.
But while these apps offer a useful log of information, including how many hours of sleep you get per night and how often you move around in your bed, sleep scientist Patrick Fuller, associate professor of neurology at Harvard Medical School, told Tech Insider, you should be wary of using them as a way to diagnose a sleep disorder.
This is because they can't do one important thing, Fuller said: They can't monitor what's going on inside your brain.
Your sleeping brain does many complicated things. It flushes out toxins and shapes and organizes your memories and thoughts. It also regulates your sleep and wake cycles, allowing you to pass in and out of the different stages of sleep.
On a good night, you'll pass through several of these light and deep sleep cycles, with your brain activity characteristically ramping up and down during each of these phases.
During a formal sleep study, called a polysomnography, your doctor will be able to see — via your brain waves — how often and efficiently you pass through these stages. To do this, they hook you up to an electroencephalogram (EEG), which evaluates electrical brain activity.
They'll also monitor your oxygen levels to ensure that you don't stop breathing while you're sleeping. If you do, you could have sleep apnea — a serious and debilitating condition that can lead to heart disease and stroke.
Tracking this feedback from your brain in addition to your body movements is very important in determining whether or not you have a diagnosable sleep problem, Fuller said.
Some sleep apps claim to measure and analyze your sleep cycles by using the phone's accelerometer to detect your movements during the night — for example, they say that if you're moving around you're in a lighter sleep stage, and if you're as still as a log you're in a deep stage. But according to Fuller, it's near impossible to diagnose the quality of your sleep based on movement alone.
The only real way to fully understand what's going on with your sleep pattern would be to submit yourself to a formal sleep study in a clinic, Fuller said.
"If I really wanted to see what was going on with myself or a patient," Fuller said, "I would want to see the EEG, and that simply isn't available for virtually any of these systems that are out there."