10 Myths About Sleep

Yawning Means You're Bored and Tired
Science is still puzzling out why we yawn. It might have more to do with temperature than tiredness. © Giulio_Fornasar/iStock/Thinkstock

You and I, on average, will each yawn eight times today [source: Koren]. While one or two of those yawns may be to pop your ears after a flight or another change in air pressure, scientists can't yet fully explain for certain why we yawn — or why yawning is contagious. But they have ruled out the theory that yawns mean you're tired. Yawning also won't help wake you up by increasing the oxygen levels in your bloodstream.

Hippocrates theorized that yawning was the body's way of releasing noxious air when body temperature began to rise. Later theories emerged that yawning was the body's way of increasing the level of oxygen in the blood supply [source: Robson]. Currently, there are two leading theories as to why we yawn. One is a social explanation: Yawning is a primitive form of communication (although what we're trying to communicate to each other remains unclear). The other explanation is that yawning is a thermoregulatory function that cools the brain when its temperature rises as little as 0.18 degree Fahrenheit (about 0.1 degree Celsius). Humans do yawn more frequently when they're in a warm environment and when feeling anxious or stressed [source: Gallup].

Author's Note: 10 Myths About Sleep

As it turns out, we spend a lot of time on using our phone, playing games, texting, using social media. When you total up all the hours, it adds up to be about 23 days out of the year. That's 23 days of looking at a small screen. I'm not judging. I like my phone just as much as anyone else. But during my research I also discovered that there are apps that can help reduce the problem that light causes on our sleep cycle. They work by filtering out blue light and are available for all your devices, from phone to tablet to computer. And they also come in physical filters. So if you must sleep with your phone, it can't hurt to try out a filter.

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