Why You Forget Many of Your Dreams? Your Brain Actively Does That

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"I had a dream last night and I woke up crying, but I just can't remember what I dreamed about!"


"I can only remember some fragments of my dreams, like someone said something, but I can't recall that 'someone' nor 'something."




Does this also happen to you? Have you ever wondered why we just forget many of our dreams? A new study carried out by researchers from Japan and U.S. showed that it might be our brains' active action.


Rapid eye movement sleep


Rapid eye movement (REM) sleep is the period when most of our dreams are made. The first REM period occurs about 90 minutes after falling asleep, when your eyes start to dart, your heart rates rising, your limbs paralyzed, and your brain waves awaken. You then start to dream.



Scientists have explored the role of sleep in storing memories for a time period longer than most of our ages. So far, it has been proved that sleep helps the brain store new memories, and REM is suggested to be the time when the brain actively eliminates or forgets excess information.


Recent studies in mice have also shown that the brain makes connections between neurons to enhance certain types of learning. However, no research had shown how this might happen until this study.


"This study provides the most direct evidence that REM sleep may play a role in how the brain decides which memories to store." Said Janet He, director of the program.



How REM influences memories


To understand the process, first you need to know about melanin concentrating hormone (MCH), a molecule that is involved in the control of both sleep and appetite. In an experiment in mice, a majority (52.8%) of hypothalamic MCH cells fired when mice underwent REM sleep whereas about 35% fired only when the mice were awake and about 12% fired at both times.


Many of the hypothalamic MCH cells send inhibitory messages to the hippocampus which is the brain's memory center. MCH cells are active during REM sleep, which means the cells may have a role in memory store of the brain.



Test of the idea


The researchers used lab mice with the genes of MCH neurons on and off. They examined the role that MCH cells played in retention, the period after learning something new but before the new knowledge is stored into long term memory.


The result showed that the mice’s memories were worsened during retention when the MCH cells were “on,” while turning the cells “off” improved memories. Further experiments suggested that MCH neurons exclusively played this role during REM sleep.



"These results suggest that MCH neurons help the brain actively forget new, possibly, unimportant information," said Dr. Thomas Kilduff, director of the Center for Neuroscience at SRI International.


"Since dreams are thought to primarily occur during REM sleep, the sleep stage when the MCH cells turn on, activation of these cells may prevent the content of a dream from being stored in the hippocampus—consequently, the dream is quickly forgotten."

13 Answers

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TY my lovely brainny, Id explode if remember every dream.
But really it really doesnt feel well when you can remembe half of your dream but not the other halt.
Some dreams...you'd better forget them.
didnt have good inspirations. its all my brains fault
Don't worry, we can rest in the next life. *hugging my brain*
nayway help remembering fewer dreams? i wake up my brain filled with rubbish i dont ffel well
I haven't dreamed for a long time.
Do u take meds to sleep
i can remember my dream when i just wake up. but 5 mins later i forget all of them.
anyone here have colorful dreams??
I dreamed in color recently. I’m can’t remember the last time I did that.
didnt have dreams for long time.  is there a research telling how bad it is if you dont have one?
I don't know how true it is, but I heard we dream every night, whether we remember or not.
We dream several times every night, but some people forget them all. This is why people can feel like they haven’t had any dreams. If a person is awakened while dreaming, and thinks really quick, there’s a good chance this person will remember the dream.
I used to remember up to 3 dreams a night (because I never slept more than an hour at a time. I started taking Trazedone to help me get better sleep, and now I don’t remember many dreams