Do we hear while we sleep?

Whoever told you that you shouldn’t go to sleep with the TV on was right. Did they also tell you the reason is because something spooky gets absorbed into your subconscious? That part is a myth. However, there is some interesting science behind how sounds are processed during sleep.

The brain doesn’t shut itself off to sound when we are sleeping. Sounds are just processed differently. There is no more absorption during sleep and probably less than when awake. The biggest difference may be our awareness of sounds and our ability to consciously pay attention and select sounds to remember. However we are not aware of everything we hear during the daytime. In fact, our brains are pretty selective.

The cocktail party

Ah yes. That thing our grandparents called parties. Anyways, ever notice when you are at a party and suddenly your inner supersonic hearing kicks in and from across a loud room you hear your friend you haven’t seen for years call out your name? While you are reconnecting with that buddy of yours, you are ignoring every other conversation in that room.

That is commonly referred to as the cocktail party effect. It’s an example of your brain’s ability to process numerous sounds and filter out that one important sound it loves to hear your own name. Another example is the conversation you are having with someone else in the middle of the loud party. Your brain is filtering out all of that other noise so you can hear what your buddy is saying.

Do we hear during sleep?

As anyone with an alarm that wakes them in the morning can attest, we can hear during sleep. Sometimes that sound can wake us up, as in the case of an alarm. Other sounds are filtered out by our brain like those sounds at a party that are meaningless to us. Whether or not a sound will wake us depends on how deep in sleep one is the volume of a sound, the difference between the sound and the background environment a sharp noise in a really quiet environment will have more of an effect than a dull sound in a room with a white noise maker on as well as the significance of a sound. As I mentioned above, we love to hear our names even during sleep. Therefore, whispering someone’s name may be more likely to wake someone than a louder more neutral sound.

Experimentally, sounds presented to individuals during wake and while asleep evoke are different. This represents differential processing of information when we are awake and asleep. Interestingly, after hearing one’s name, there is an identical enhancement of an electrical signal persisting in both sleep and wake states. In other words, your brain’s love for your name is wired in.

Don’t leave the TV on.

If you leave your TV on at night, it might take you longer to fall asleep, you might not get as much deep sleep and you might wake up earlier in the morning decreasing the amount of sleep you receive. Since sleep is as important as eating and other bodily functions, you don’t want to do that. Some people recommend not keeping a TV in the bedroom, but leaving it on while sleeping is certainly a bad idea.