* It may be easier to remember the dreams you have in the last hours of sleep, right before you wake up.
* Rapid eye movement (REM) sleep is the best for vivid, hallucinogenic dreaming.
* If you think you’ve never dreamt, you’ve probably just never been woken up in this REM dream phase, the sleep stage that follows our deepest sleep.
* Dreams that are more emotional are also longer and easier to remember.
Your dreams are important.
Sleep scientists are learning that what happens to your brain when you snooze is essential for having a good life. Dreams help us problem-solve, soothe emotional ups and downs, and even make some people more creative.
But only some of our dreams get remembered.
Neuroscientist Matthew Walker has been trying to figure out the reason why for years. In his new book, Why We Sleep, a how-to guide for sleepers, he explains how dreams are “nursing our emotional and mental health.”
And he says there are a few key reasons we remember some of our dreams, but not others. Here are two of the biggest, according to Walker.
Our most psychedelic dreams stick with us
We sleep in roughly 90-minute cycles, which are broken up into different stages of sleep, some heavier and some lighter. We technically dream in every single stage, Walker says. But the phase known as rapid eye movement sleep (REM) follows our deepest sleep cycle. REM is our brain's most psychedelic sleep period — when Walker says we have “the most vivid, hallucinogenic, narrative, memory-laden dreams.”
Babies get a ton of REM (about 50% of their sleep time) while the rest of us are in REM for about one fifth of our night.
Even though the body is completely paralyzed, the brain is hyperactive here. Visual perception and movement centers of the brain light up on MRI images, showing that the amygdala and hippocampus (the memory and emotion centers in the brain) are buzzing with life. Walker says these regions are up to 30% more active in REM sleep than in waking hours.
As we sleep, the REM portion of our sleep cycle becomes longer, and we're more able to remember those dreams.
That's why Walker says it's more likely you'll remember a dream that you have in the close-to-waking sleep hours than one that happened right after you went to bed.
Dreams that are more emotional are also easier to remember
In "dream reports" patients write when they wake up in Walker's lab, more emotional dreams are accompanied by longer dream diary entries. His research suggests that people who aren’t remembering their dreams probably just aren’t waking up at the right time.
When Walker brings patients into the lab and forces them awake during the REM stage, he says many tell him it's the first time they have remembered a dream.
This isn't because sleep lab conditions are any more dream-inducing than a participant's own bed. "It's just the first time that we've been able to actually get them to recall their dream, because we've woken them up right in the midst of REM sleep," Walker said.
Dreams allow us to spin our daily lives into nighttime narratives, or do a kind of self-therapy on the painful stuff that pops up. It just takes a certain touch at the right time to remember them.