▲Blind people also dream, but those who were born with the condition can only sense things like sounds, smells and emotions. Those who have turned blind over their lifetime can 'see' people and sights in their dreams.

▲Previous studies revealed that about 12% of us dream in black and white. However, a more recent survey set that number lower, at 4.4%. According to research, the invention of color films may have led to this decline in percentages.

▲It's normal to forget what we dream about. This happens because our mind gets rid of half of what we dream after 5 minutes. After 10 minutes, you will already have forgotten 90% of a dream!

▲We all dream whilst we sleep, although we don't often remember what about. Only in exceptionally rare cases of problems with the psyche are people unable to dream.

▲Negative emotions are also more common in dreams than positive ones, which means that we have more nightmares than good dreams, even though we usually don't remember either.

▲One of the most common emotions we feel when we dream is anxiety.

▲Not all our dreams are completely random, as they contain symbols and situations from our real lives.

▲The people that appears in our dreams are faces that we know. Whether we consciously remember them or not, will will have come across that person at some point in our lives.

▲On average a person will dream in between 4 and 7 times a night.

▲REM is the stage of sleep where our eyes move rapidly even though we are not awake. During this phase, which can last from 90 to 120 minutes at a time, we dream the most deeply and vividly.

▲Animals also dream whilst they sleep. Studies revealed that different animals had similar brainwaves to humans.

▲External stimuli from our surroundings are often incorporated into our dreams by the human brain, such as a ringing alarm clock or knock on the door.

▲Men and women dream in different ways and of different people. For example, 70% of the people in men's dreams are male.

▲Some dreams can bring us premonitions whereas others can revisit the past. Research has indicated that 18% to 38% of people have envisaged future situations in their dreams whilst 70% have dreamed of something that already happened.

▲When you dream, your brain is busy trying to resolve everyday problems. If you're learning a new skill or studying new material then your dreams can really help!

▲Even though it has not been scientifically proved, some studies show that people do not dream when they snore.

▲Up until the age of 3 years old, children do not appear in their own dreams. Instead they dream of other images.

▲Dreams where a loved one is ill or dies are also very common, and usually mean that we are afraid of losing something in real life.

▲In other types of dreams, you are usually running late and miss a bus or train by a fraction of a second. This could mean that in real life you have missed an important opportunity.

▲There are some dreams which tend to have meanings in real life. For example, if you dream that you are lost and don't know the way then this can mean that you have a big decision to make.

▲Dreaming that you are being followed by someone or something can turn into a terrifying nightmare. A possible meaning behind this could be that you feel threatened by something in real life.

▲This is also one of the most common types of dream. A person will typically dream of falling from a high place if they are feeling emotionally insecure about something in real life.

▲Dreaming of water is very normal, and can mean simply that you are thirsty or need to go to the bathroom.

▲Each person dreams for between one and two hours on average, meaning that we will dream several times in one night.

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Even though these different types of dreams can mean certain things, none of these meanings are 100% accurate as each person is different.

▲Studies also reveal that our mind is more active when we dream than when we are awake! Even though our bodies are resting whilst we sleep, our minds are at work solving problems and learning.

▲Whereas women dream about men and women in an even ratio.

▲Studies show that people who are trying to give up smoking have dreams which are much more vivid.

▲People who are woken during the REM phase remember their dreams more clearly and vividly than those who sleep through the whole night.

▲It is normal for kids to have nightmares, especially between the ages of 4 and 7 years old.

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Dreaming is still a mystery for humans. During this phase of deep sleep, we imagine vivid and fantastical stories which may or may not be related to our own real lives. Even though the world of dreams is one which remains shrouded in mystery, there are some concrete facts we know are true for everyone.

Here are 30 curious facts about this deep phase of sleep that you never could have dreamed of!