Our brains are phenomenally complex instruments, and scientists are still just scratching the surface of what the brain can do. Sleep researchers are now exploring some of the myriad ways our brains and bodies interact during sleep, facilitating learning and healing as we dream.
Our brain waves affect how we react to sound at night.
Have you ever heard a sound and startled awake at night? Or slept through sounds that woke everyone else up? Specific patterns of brain activity (brain waves) called sleep spindles and K-complexes may be the reason.
Recent research shows that different brain waves have a different impact on the way your brain (and thus your body) reacts to sound during light sleep. A Belgian sleep study reported in Science Daily showed a significant variation in brain response to sound stimulus depending on which brain waves were active at the time – in other words, whether the brain showed a reaction to the sound.
What makes this study stand out?
While a great deal of research has gone into measuring and understanding the various stages of sleep, this study is different because it examines two types of brain waves that occur in a single stage of sleep: Stage 2, also known as N2 or light sleep.
Light sleep occurs while drifting off, on the way to the deeper sleep stages culminating in Stage 5 or REM (Rapid Eye Movement) sleep. Light sleep also occurs repeatedly throughout the night. Sleep spindles and k-complexes tend to alternate during stage 2 sleep and may not last more than a minute or two at a time.
This rapid shifting between the two types of brain waves is well documented, so their obvious effect on how we respond to sound during sleep is particularly interesting. One minute, we’re ready to wake up and react to danger, the next we’re in a “dead sleep” – though by classic definitions we’re still only sleeping lightly.
Why would our brains do this?
Researchers think that the added protection against waking during sleep spindles might indicate that the brain is undertaking an operation that shouldn’t be interrupted—a kind of biological lock-out. Essential brain functions that probably take place during sleep, like consolidation of memories, might happen during sleep spindles when the body is less likely to be unintentionally woken.
Have you ever slept through something that woke up everyone else? Or startled awake at the slightest sound?