Hi,
I just fell asleep in class with the camera off and when the professor called my name to make sure my group was ready to present I immediately woke up to say that I was in the lecture and almost had a heart attack because missing this specific lecture is an automatic fail. I wanted to ask anyone as to why we wake up if someone calls our name even when we’ve been asleep for 10+ minutes, but don’t wake up when hearing other people’s names or the lecture content.
In: Biology
When you fall asleep, parts of your brain turn off or do tasks they normally don’t when you’re awake.
Some parts of your brain remain on for survival. These include a lot of brain near your spine, called the “cerebellum”. They handle automatic tasks like breathing and reflexes (like when you put your hands up to block fast objects near your eyes). Although most of your brain does shut off, the signals for most senses are located near the cerebellum and stay on even in sleep. They can trigger wake-up reflexes if one of your senses is giving unusual signals that don’t appear like normal sleeptime signals.
Some of those reflexes are triggered by noise and they wake you up if a noise meets a checklist that brains have evolved to recognize as *potential danger*. These include loud, sudden noises like thunder, or the voices of other people.
Brains are also very good at filtering out noise. If you have a good memory for dreams, you’ll notice that a lot of loud noises or arguments that don’t seem directly threatening will influence the dream you have. Putting these senses *inside* the dream seems to suppress wake-up reflexes, but I’m not too familiar with why that would be. Some people even hallucinate hearing people talking while falling asleep, which is probably when the brain starts to turn dreams on.
While asleep, the brain doesn’t need to have details about lectures or how your blankets feel. So it filters that data out and continues to rest.
Your brain does still process sounds from your environment even while you’re sleeping. Obviously it would be detrimental to your sleep to awaken for every sound, so you’re able to “tune out” a lot of unnecessary stimuli. You’re able to recognize important sounds, though, like your own name or one of your children or pets in distress. How much you’re able to process and how fast you wake up will depend on the stage of sleep that you’re in.
There’s even some research that shows that when you’re sleeping in an unfamiliar environment, you “sleep with one eye open” by sleeping lighter and remaining more alert to more potential threats.
I’m not a doctor but I believe it’s due to the Reticular Activating System (RAS). Its a bundle of nerves in your brain that is responsible for filtering information. A typical example of its function is hearing someone say your name in a noisy crowd. I believe it’s also like a watchdog when you sleep so you dont sleep through someone breaking into your house.
Your brain stores different words in different ways depending on their meaning and importance. For example, swear words are stored in a totally different way and that’s part of what gives them their power in our speech. One such word that has extra importance is our name. Our brains are constantly on the lookout for our name because hearing it means we’re needed.
Also, when we’re asleep, our bodies are silently processing stuff still and absorbing information. That’s why you might wake up to a loud noise or someone nudging you.
Combine these two things and now you have a brain that will wake you up when your name is called.
When you’re asleep you’re not 100% unconscious; you’re just asleep, but your are still recognizing some sensory input. Your mind has just set it to ‘low priority’ but if it gets a trigger that’s important your brain will wake you up.
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