Almost everyone dreams. Some dreams feel vivid, some feel real, and some are emotional, but most of them disappear the moment we wake up. But why does the brain create dreams in the first place, and why do most of them vanish from memory?
Scientists say dreaming is closely tied to how our brain processes memories, emotions and information while we sleep.
Dreams mostly occur during a stage of sleep known as Rapid Eye Movement Sleep, or REM sleep. During this stage, the brain becomes almost as active as it is when we are awake. Brain scans show that many regions involved in memory, emotion and imagination become highly active.
In today’s The Daily Why, a new series from India Today Science, we try to understand the mechanism that triggers dreams and the one that makes us forget them.
HOW DO DREAMS FORM IN THE BRAIN?
Inside the brain, several areas work together to produce dreams.
The Hippocampus helps process memories from the day. At the same time, the Amygdala, which is the emotional centre for processing fear and memories, becomes highly active. That is why dreams often contain strong emotions such as fear, excitement or anxiety.
Meanwhile, the Prefrontal Cortex, the part that normally controls rational thinking, becomes less active during REM sleep.
This unusual combination explains why dreams can feel emotional, strange and sometimes illogical. The emotional parts of the brain are active, but the logical “editor” is partly switched off.
Scientists believe dreams may help the brain organise memories and process emotions. While we sleep, the brain replays fragments of experiences from the day, mixing them with older memories and imagination. These pieces combine into the stories we experience as dreams.
WHY DO WE FORGET MOST DREAMS?
Even though we may dream several times each night, most dreams are forgotten within minutes of waking up.
One reason involves brain chemistry. During REM sleep, levels of a chemical called Norepinephrine drop sharply. This chemical normally helps the brain store memories.
Because norepinephrine levels are low during REM sleep, the brain struggles to transfer dream experiences into long-term memory. In simple terms, the brain experiences the dream but doesn’t “save” it properly.
Another reason is that the memory-forming hippocampus is not working at full strength during dreaming. Without strong memory encoding, the details of dreams fade quickly once we wake up, and our brain shifts into normal waking activity.
WHY DO WE REMEMBER SOME DREAMS?
Dreams are most likely to be remembered when a person wakes directly from Rapid Eye Movement sleep, the stage when vivid dreaming occurs. If someone wakes during another stage of sleep or quickly drifts back to sleep, the dream memory fades quickly.
Studies show that people can forget a dream within five to ten minutes if they do not recall it immediately. Dreams that involve strong emotions, unusual events or personal meaning are easier to remember because the brain’s emotion centre, the Amygdala, is highly active during REM sleep.
Once awake, the brain focusses on real-world stimuli, and new information rapidly overwrites fragile dream memories.
Scientists estimate that people can have four to six dreams each night, but most disappear before we even sit up in bed.
Researchers are still studying the deeper purpose of dreams. Some theories suggest they help us practise dealing with emotions or prepare the brain for real-life challenges.
What scientists do know is this: while we sleep, the brain is far from quiet. Instead, it is busy replaying memories, processing emotions and weaving stories, even if we rarely remember them by morning.
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