You were tossing and turning all night, and you remember the dream you had so vividly, as if it really happened. It’s almost like your dreams kept you up all night. Wait, that doesn’t make sense. If you were dreaming then you must’ve been sleeping soundly, right? So does dreaming mean you’re getting good sleep? Or does it mean you went on an excellent adventure at the expense of your beauty rest? Well, there's not exactly a straightforward answer, but there is an explanation for both sides of the debate. As with most things in the sleep world, though, it's just a little bit complicated.
To tackle this question, it's important to understand what's actually happening in your brain and body when you're sleeping. According to the American Academy of Sleep Medicine (AASM), there are five stages of sleep, which repeat throughout the night about every 90 to 110 minutes. The first two stages involve light sleep and slow brain waves (like the kind of sleep you get during a quick catnap), and the third stage is when you're the most "out of it" — aka when it’s the hardest to be woken up from your slumber. The last two stages are when REM (rapid eye movement) sleep happens. In REM sleep, per the AASM's breakdown, your breathing picks up, your eyes flutter beneath your eyelids, your body moves into a deep sleep, and it's also when your brain activity is heightened enough for you to experience vivid dreams.
"REM sleep is one of the most important stages of sleep because it rejuvenates the body, mind, and helps out with your memory and health," Dr. Rajkumar (Raj) Dasgupta, an assistant professor of clinical medicine at the University of Southern California's Keck School of Medicine, who's also part of the AASM, tells Elite Daily in a phone interview. "REM dreams are those vivid, [high-definition] quality dreams."
But even though REM sleep typically means 1) that you're in a deep sleep, and 2) that you're likely dreaming, Dr. Dasgupta says it's possible to dream a lot throughout the night and not get a good night's sleep. "Actually, we dream in all stages of our sleep," he clarifies. "When you have those dreams where you think you have a dream, but you can’t figure out the details because it feels like a VHS recording? That’s a non-REM dream," he explains. In other words, sometimes you dream during one of those earlier, lighter stages of your sleep cycle, but when that happens, you usually forget a lot of the details of the dream because you weren't really that deep in your slumber.
Dr. Dasgupta tells me he measures good sleep based on both quality and quantity. "Quantity depends on age, but a ballpoint is between seven and eight hours a night for adults. If you’re getting a good quantity of sleep, but still having symptoms of not a good rest, then that means you’re not going into the deep stages of sleep. You have frequent awakenings," he explains, adding that obstructive sleep apnea — which affects 15 to 20 million people on average, and is a condition wherein your breathing repeatedly stops for brief moments throughout the night — could be what's "waking [you up] before you can get into those deeper stages of sleep."
So basically, it is possible to dream without getting a good quantity of quality sleep.
But, if you're having those vivid REM dreams, then that's usually a sign you're getting good sleep, according to Dr. Dasgupta. What's more, when you're getting a good night's sleep and experiencing REM dreams, it can actually improve your ability to do certain things when you're awake. In a 2009 study reported by TIME, researchers from the University of California, Berkeley found that REM sleep can play a role in how well you read other people's emotions. The study found that people who reached REM during a nap were able to judge facial expressions with better accuracy than those who didn't reach REM — which kind of makes sense when you think about it, since, when you're more well-rested, you tend to be more present, alert, and aware, right?
Similarly, a study published in the scientific journal Current Biology found that, if you learn a new task and then sleep on it, you could be up to 10 times better at that task compared to someone who stayed awake. Hello, study breaks.
So, dreaming might not always mean you're getting a quality night of sleep. But when it does, rest assured, your brain's probably getting a nice boost, too.