We’ve all been there, you’ve just won the lottery, and you’re kicking back in the hot tub, indulging in your favorite beverage. Then, all of a sudden it’s gone. Your alarm clock rudely awakens you and you come to the sudden realization that your life is considerably less glamorous than in your dreams. Oh, bollocks.
But then something strange happens, five minutes pass by and you’ve forgotten most of, if not all of your dreams and that’s if you’re lucky, sometimes we have dreams we’re not even aware of, because we can’t remember even having them, after we’ve awoken.
Why is this? Why do we so easily forget our dreams? Let’s find out.
The brain is the last major mystery of the human body. There are so many aspects of the brain that continuously baffle scientists and one of those is sleep. Scientists aren’t even one hundred percent sure why we even need sleep. So when it comes to understanding dreams, we’re still very much in the dark. We have many theories of course.
One of the most popular theories is that when we sleep our brains are filtering through the day’s memories and deciding which ones are important enough to keep permanently and which to ditch. Scientists think dreams are a visual representation of this process. Based on that theory it makes sense that in order to understand dreams further we should study the two parts of the brain that are largely responsible for processing memories.
Those are the hippocampus and the neocortex. And that’s exactly what researchers at the California Institute of Technology did.
First let’s talk about the hippocampus, which you may be surprised to know, is not a college campus for hippos it’s actually named after its resemblance to a seahorse. This is the part of our brains where memories are formed.
However, it’s thought that during sleep these memories get transferred to the outer layer of our brain, the neocortex, where they are permanently stored. Think of it like a digital camera. The hippocampus is the camera’s sensor; the neocortex is the memory card. For a memory to be transferred from the hippocampus to the neocortex the two parts of the brain have to be connected via neurons, which are responsible for transmitting information around our brains. If your brain were the Internet then your neurons would be the routers.
The hippocampus and the neocortex do this by firing electrical signals from their neurons at exactly the same time, several times per second. Imagine the two parts of your brain are having a conversation about the events of the day i.e. your memories. When they both fire their neurons at the same time and they are in sync we know they are communicating with each other.
Scientists call this “neural chatter”.
Researchers at Caltech used brand new technology to listen in to these two parts of the brain in rats, whilst they were sleeping. They found that whilst the rats were in a stage of the sleep cycle known as slow-wave sleep, more commonly referred to as “deep sleep”, the hippocampus and neocortex were perfectly in sync. Their neurons were firing at the same time. From this, we can presume that the two parts of the brain were talking to each other and memories were being recorded. But here’s where dreams come in. During the slow-wave sleep phase, we don’t have any dreams, this is known as a dreamless sleep state.
The researchers then did the same thing whilst the rats were in the rapid eye movement or R.E.M. sleep stage. What they observed, once and for all, answered why we have a hard time remembering our dreams. During the R.E.M. sleep stage, the hippocampus and neocortex were still firing their neurons, but not at the same time. They were no longer in sync. To put it in other words, they were still having conversations, but not with each other.
This means during R.E.M. sleep memories don’t get recorded to our brain’s databank, the neocortex and R.E.M. sleep is when the majority of our dreams occur. So the memories of our dreams are still being created, they’re just not being stored permanently. We remember only very faint aspects of our dreams, because very occasionally the neurons might, by chance, fire at the same time, but the majority of the time they don’t. Some people believe this is because dreams are non-essential to life; they’re no more than a by-product of the creation of new memories during our sleep. So what’s the point in remembering them? They don’t serve a purpose.
But for whatever reason, we don’t remember our dreams, simply because during a certain stage of our sleep, two very important parts of our brain, which are both responsible for memory, don’t get on with each other very well. To be honest, it’s probably for the best; some of the weird stuff we do in our dreams is definitely best forgotten.