The brain has a "delete key"

You know the feeling. You wake up and the dream is still there, whole. There was a house, someone was telling you something, and it was perfectly obvious why all of it made sense. You reach for it - and it’s gone.

It doesn’t fade. It goes. As though someone hit a key while you were still opening the file of the dream.

This has been happening to you almost every night of your life and you’ve probably never once asked why.

The answer is insultingly simple: because something is deleting it.

The delete crew

In the hypothalamus there’s a group of neurons that release a substance called MCH. They fire only during REM - that is, precisely while you’re dreaming - and their job is to suppress the hippocampus, the part of the brain that turns experience into lasting memory.

So it isn’t a fault. Not stress, not bad sleep, not age. There is a dedicated system and it runs to a schedule, no excuses.

And why would anyone want that

The loveliest explanation came from Francis Crick. That in sleep the brain takes out the rubbish - connections that piled up during the day and are of no use to anyone.

If it weren’t so, remembering our dreams would be no gift but a problem. We’d be filing the waste instead of getting rid of it.

One shocking sum - we dream about two hours every night. Across eighty years that comes to roughly six and a half years. Six and a half years of some kind of life our brain made, and we aren’t allowed to keep a single frame of it.

While we sleep the brain is not the camera, it is the editor - and every night, without asking, it decides what goes.

And in the morning you get up thinking you’re the same.

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The video is below, the channel is Zavan. There’s more in there that I didn’t want to give away; if you find this fascinating, watch the whole thing.