Thanks in part to the internet, we have become more aware of the many benefits of a good night’s sleep. The positive benefits range from improved cognitive function and mood to better cardiovascular and metabolic health. Because of these pluses, there has been a flood of devices purporting to help us achieve this goal. Many, if not most, are available on our smart phones. Before you rush into them, I think you should be aware of some of the following facts.
The majority of apps that attempt to tell you whether you are asleep or awake are accelerometers. They detect movement and correlate its presence with being awake and its absence with being asleep. Accelerometers are somewhat accurate, although they do tend to misidentify wakefulness as sleep and thus may overestimate your sleep time, as was demonstrated in the only study using simultaneous in-lab polysomnography.
There are a number of apps that claim to tell you the quality of your sleep, alleging the ability to be able to differentiate lighter and deeper stages of sleep. However, in many studies, the most sophisticated medical accelerometers called actigraphs have been tested under stringently controlled conditions. Unfortunately, there has never been a study that could demonstrate the capability to differentiate light vs. deep sleep. As a sleep specialist who interprets sleep studies every day, I can tell you that the degree of movement between lighter stages of sleep, deep sleep, and dream sleep is very subtle and it is the accompanying brain wave patterns that are necessary to make this determination accurately. Therefore, at this time, until there are independent studies to verify this, I would be very wary of these claims.
Other apps available appear to be useful in inducing and maintaining sleep. Pink noise is a blend of high and low frequencies that produces an entrancing waterfall effect. It has been shown to decrease the time it takes to fall asleep and produce more stable sleep.
Binaural beats is found in another app. This is a method of using sounds of different frequencies to produce what is called brain synchronization. In this method, two sound waves of different frequencies are introduced into each ear. The waves of similar frequency are cancelled out by the brain, thus leaving the difference between the two. If the difference is in the low frequencies, characteristic of sleep, some studies have shown that the brain can become synchronized with these frequencies and enter into sleep.
Finally, there are apps that utilize techniques such as meditation, guided imagery, muscle relaxation, and even hypnosis to help you get to sleep. I think these can be quite useful. However, keep in mind that for these to work you need to combine them with good sleep hygiene. If you are on the computer or texting right up until bedtime or consuming caffeine too close to bedtime, it is unlikely any of these will be effective for long.
