Wellness, Home & Lifestyle, Science & Tech

The Absurd Act of Dreaming

Matthew Walker

Lesson time 13:11 min

Ever wonder what your brain is doing when you’re dreaming? Matthew explains why dreams can benefit our waking selves.

Students give MasterClass an average rating of 4.7 out of 5 stars

Topics include: When We Dream • A Freudian Mistake


[MUSIC PLAYING] - Last night, if you slept-- and I very much hope that you did-- when you went into dream sleep, you became flagrantly psychotic. And, in fact, you did that several times throughout the night during those REM cycles. Now, before you reject my diagnosis of your nighttime psychosis, let me give you five good reasons because, first, last night, when you started dreaming, you began to see things which were not there, so you were hallucinating Second, you believe things that couldn't possibly be true, so you were delusional. Third, you became confused about time, place, and person, so you're suffering from disorientation. Fourth, you had wildly fluctuating emotions, something that psychiatrists call being affectively labile. And then how wonderful you woke up this morning and you forgot most, if not all, of that dream experience, so you're suffering from amnesia. If you were to experience any one of those five symptoms while you're awake, you would be seeking, perhaps, psychological or psychiatric intervention. But yet, for reasons that we're only now just starting to understand, this seems to be both a normal physiological and psychological process each and every night. REM sleep and the associated conscious experience that we have during REM sleep that we all call dreaming really is a case of how your brain goes completely out of its mind. Dream sleep, or REM sleep, is brain activity that seems to be almost indistinguishable from that when we're awake. With the advent of more powerful MRI scanning technology, we've been able to look deep within the brain itself. And, during these studies, we have people go inside of a scanner, and we have them fall asleep. And, when they go into REM sleep, we turn on the scanner, and we can start to look at the changes in their brain activity. In fact, some parts of your brain are up to 30% more active when you go into REM sleep than when you are awake. And, firstly, what we found is that regions at the back of the brain that are associated with visual processing, what we call your visual cortex, those areas burst into life. There's also motor areas of the brain that control movement and this sort of sense of kinesthetic movement activity. Those light up in their activity. But there is another brain area that does something in the complete opposite direction, and particularly, the left and the right side of your prefrontal cortex. Now, you can think of your prefrontal cortex a little bit like the CEO of your brain. It's very good at making high-level, top-down, rational judgments, logical decisions. And it also helps control our emotional impulses. But this part of the brain, when we shift over into REM sleep, goes in the opposite direction of all of those other areas. It is actually switched off or deactivated during REM sleep. So how does this help us understand the dream state? We see visual areas lighting up, motor command areas lighting up, memory and emotion areas lighti...

About the Instructor

As a professor of neuroscience and psychology at UC Berkeley and the director of the Center for Human Sleep Science, Matthew Walker is an expert on sleep. In this class, he will illuminate the science behind sleep and teach you how to increase the quality and quantity of your sleep. Learn how to prevent sleep debt, navigate the effects of alcohol and caffeine, and improve your health. Your best sleep starts tonight.

Featured Masterclass Instructor

Matthew Walker

Neuroscience professor Matthew Walker teaches you the science of sleep and how to optimize it to better your overall health.

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