Some mornings, waking up might feel like interrupting a vivid alternate universe. You open your eyes to reality, but the dream you were having still lingers clearly in your memory, complete with characters and plot points. Other days, waking up may be more akin to emerging from a black void with nothing to report.
Even if you rarely recall details of your dreams, chances are you’re still having them. Research indicates that nearly everyone dreams regularly–even those who claim they never do. “If you bring those same people into the sleep laboratory and wake them up during an active stage of sleep and ask what they were thinking, they will remember something,” says Erin Wamsley, an associate professor of psychology and neuroscience at Furman University, where she studies sleep and dreaming. “In sleep lab conditions, where everyone is forced to immediately reflect on dreams, most people remember at least one dream in a night,” she tells Popular Science. (The one exception seems to be people who lose the ability to dream, as a result of brain damage or disease in specific regions, and this comes with other profound effects.)
Dreaming is a relative constant, it’s just memory that varies. There is no single answer for why, and lots about dreaming remains unresolved. But science can offer hints for why dreams can be so hard to hold onto.
First, dream memory is generally short lived. Sleep studies show it’s rare to remember a dream if you don’t awake during or immediately after it, and then stop to consider what you experienced, says Wamsley. We recall our dreams best when we pay attention to them while conscious, she explains, otherwise they fade away. That’s potentially because of differences in neurotransmitter activity that occur when we’re conked out. Waking during the night is associated with better dream memory, and it’s actually quite normal to stir for a few seconds at a time and shift positions, Wamsley says. Be warned though, past a certain threshold, frequent waking translates into lower quality sleep. “Poor sleep is often associated with high dream recall…Having a few arousals is normal and healthy. Having a really large number is often part of a sleep disorder.”
On its own, waking up is important for dream memory. However, when and how you wake up also matters. Sleep phase, timing, and alarms all play a role.
Sleep occurs in four distinct stages: rapid eye movement (REM) sleep and then three types of non-REM (NREM) sleep which repeat in a cycle throughout the night. NREM 1 sleep is the lightest stage and the first you fall into from waking–it only lasts a few minutes at a time. Then, during stage 2 NREM sleep, your brain waves slow and electrical activity comes in short bursts. Nearly half of adult sleep time is
