The human brain is fascinating and bizarre, and even the most advanced scientists still don’t understand exactly how it works. One of the strangest phenomena that the brain produces is dreams. What are these sleeping hallucinations and why do we have them? There are many theories as to why we dream, but no one really fully understands the science of sleep and dreaming.

Here are ten of the strangest facts about sleeping and dreaming:

1. Within five minutes of waking up, you have already forgotten 50% of your dream. Within 10 minutes of awakening, you will have forgotten 90%.
2. People who have been blind since birth do not see images in their dreams, but they do dream about smells, sounds, sensations, and emotions.
3. Your mind does not invent characters for your dreams, as any human face in your dreams is someone that you have already seen before. You might not consciously remember seeing them, as they might have been just a face in the crowd, but your mind stores in your subconscious.
4. The most common emotion reported to be experienced in a dream is anxiety.
5. Not being allowed to dream can make you crazy. A study showed that people who were woken up and not allowed to experience the Rapid Eye Movement stage of sleep when dreams occur, experienced a vast array of psychological symptoms within only three days including irritability, loss of concentration, and hallucinations. As soon as they were allowed to dream again, their brains compensated by increasing the percentage of REM sleep within their sleep cycle.
6. The outside world can enter your dreams. While you are sleeping your senses are still alert and outside stimuli will have an effect on what you are dreaming. Have you ever had an outside noise incorporate itself into your dream, or dream that you are drinking water and then wake up to find that you are very thirsty?
7. Statistics show that 1% or less of the adult population is prone to sleepwalking.
8. There have been many famous reports of dreams predicting the future. A few days before he died, Abraham Lincoln was said to tell his wife about a dream that he had. He was looking at a coffin surrounded by hundreds of people mourning. A soldier beside him in the dream told him that the president had been assassinated.
9. The dreaming stage of sleep, known as “REM” stage, is beneficial in helping us learn. When we dream, the cerebral cortex is stimulated and protein is increased in the brain, helping us to increase our mental power and develop new neural pathways in the brain.
10. The most common negative dreams include falling, being chased by something, being at school, and having your teeth fall out.