Although there are five stages of sleep, REM dreams occur only during the rapid eye movement (REM) cycle of the night. REM sleep can occur multiple times, up to three or four times a night. Each cycle lasts up to ninety minutes. REM sleep is the period during which you experience the complex and 'story-like' dreams you often remember in the morning.
Importance of Sleep: REM Dreams and Memory
When entering REM sleep, your brain stops sending messages to your spinal cord. This means you are completely immobilized for the duration of your REM cycle, protecting you from acting out your dreams while sleeping. A relatively rare disorder, called "REM sleep behavior disorder," exists where a person does not become immobilized during REM sleep. When people with this disorder get up and act out their dreams while still sleeping, they easily get into accidents and injure themselves. Although the two are often confused, this disorder is not the same as sleepwalking, which does not take place during the REM cycle.
Although we don't really know what makes sleep important, REM dreams appear to play an important role. The exact reasons for dreaming are still unknown, but several theories exist based on some factual observations. For example, adults spend only twenty percent of their sleep time in REM sleep. Infants spend nearly fifty percent in their REM cycle. During childhood, a tremendous amount of learning takes place, and REM dreams are thought to play a role in this. This theory is further supported by the fact that adults who are taught new skills, but are then deprived of REM sleep, often cannot remember what they were taught.
The exact way in which our REM dreams help us learn or remember new things is unknown. We do know that people who sleep less, or who do not get sufficient REM sleep, are generally more forgetful.
One leading theory is that memories are consolidated while you sleep. Your brain is thought to make connections between the sensory input you experienced during the day and your emotions. During REM sleep, links are made between your new and old experience. This helps you remember information better after, literally, sleeping on it. Essentially, your brain moves information from your short-term memory to long-term memory during REM cycle dreams.
Although many scientists believe dreams are related to our memory processing, there are some other theories about dreaming as well.
Freudian Dream Theory
Sigmund Freud has another theory about dreaming. He suggested that dreams are a representation of our unconscious thoughts, wishes, and motivations. He believed the desires and thoughts from our subconscious float to our awareness through our REM dreams. Freud's theory contributed to dream interpretations, which remain popular today. However, there is no conclusive proof that dreams have symbolic or predictive meaning.
The Activation-Synthesis Model
J. Allan Hobson and Robert McClarley suggested the Activation-Synthesis theory on dreaming. The hypothesis is that during REM sleep, different neurons activate those areas of your brain that are involved in emotions, memories, and sensations. The brain then tries to interpret these signals, which results in REM dreams. This theory suggests that the brain believes the signals it is sending and receiving are "thoughts", and tries to interpret these signals by producing pictures and sounds.
Using Your Dreams
The reasons we dream are still unknown, and bound to be complex. Whichever the reason might be for dreaming, it can be time very well spent. Allegedly, the idea for monster.com came to founder Jeff Taylor in a dream. Even if dreams are a semi-random association of thoughts, images, and feelings, the combination of these could result in a good idea. The key to using these great ideas is remembering your dreams.
Remembering Your Dreams
If you wake up at the end of a REM cycle, you are most likely to remember your dreams. Unfortunately, this is something you have no control over. People who stay in bed for a few minutes after waking up, thinking about their dreams, do tend to remember them better. If you want to remember your dreams, keep a note pad by your bedside, and write your dream down immediately after you wake up. Usually, you forget your dreams minutes after stepping out of bed. Writing them down first, while you are still waking up, can help you recall them for a much longer time.