It has been said that we all dream around 3-6hours per night and that each dream lasts around 5-20 minutes.
There are two types of dreams: REM sleep and non-REM sleep. REM sleep accounts for around 20-25% of your night’s sleep and seems to only occur in mammals from studies. REM sleep occurs as signals from the inner base brain region called the pons travel to the thalamus and then back to the outer region called the cerebral cortex which is vital for organizing information and therefore learning and thinking. It is also during REM sleep where many proteins are made. The pons region also causes a temporary paralysis during your REM sleep as it sends signals to shut off spinal cord neurons that would otherwise cause you to act out your dreams. There are diseases where these signals are not inhibited and dreams are acted out which can cause very dangerous situations.
As the cerebral cortex is involved it is believed REM sleep is important for children to learn whilst they are young as many studies revealed how infants spend many more hours in REM sleep than grown-ups. Another study showed also the importance of REM sleep for learning certain skills as after being deprived of either non-REM or REM sleep after being taught a new skill, only the individuals deprived of REM sleep could not recall it the next day.
An idea might be (believed by some) that as signals are received by the cortex, which always tried to organize information, it tries to make sense of all these messages and thereby creates a dream story.
What do you think?
I also find it highly interesting that most mammals have REM sleep. This indicates that my sisters dog for instance also has dreams. I often see her running around and barking or talking in her sleep. My sister mentioned to me she had read somewhere how dogs dream more about smells and emotional feelings; how they feel about frustration towards their owner, how much they love them or that they are hungry, however according to this study she read they apparently do not dream very much from a sight sense perspective. I myself hardly ever recall sounds and feelings but mostly my sight sense. But perhaps people with different limitations in life (such as the blind) dream more frequently with different senses?