Does everyone dream?

All humans dream. (And as most mammals and birds experience REM sleep, it’s presumed that they do, too.) When people say, “I don’t dream,” they’re really telling you that they don’t remember their dreams. Remembering is easier if you wake up in the middle of a dream or almost immediately afterward. Consequently, light sleepers, who are apt to wake up frequently during REM sleep, generally have better recall than their sound-asleep bedmates. Remembering is also easier when you awaken naturally, like on the weekend or during a vacation. The jolt of an alarm clock, on the other hand, is liable to make your thoughts jump abruptly from a fantasy dream to a nagging to-do list.

Why are dreams so weird?

There’s a biological reason. The prefrontal cortex of the brain, responsible for logic and reasoning, is inactive during sleep, thus allowing all sorts of crazy images to evolve uncensored. And as your dreams are linking new memories to old ones, those associations often turn out to be a little kooky. “Dreams use so many bits and pieces of our memory, but not in a logical, linear way,” says psychologist Rosalind Cartwright, Ph.D. “It’s more of an associative conglomeration of things.”

Still, while the associations sometimes seem unconnected, if you look at the images symbolically, they might start to make sense. For example, a dream that combines flying, a childhood swim meet, and your college graduation seems outlandish, but upon closer inspection, you notice that the images all relate to feeling confident. Perhaps this theme pertains to a current challenge you are facing and your desire to be brave.

Or maybe not. Some of our dreams may be a haphazard mishmash of thoughts. “In the same way that we have lots of silly, trivial, bizarre thoughts during the day, we shouldn’t expect all our dreaming thoughts to be especially profound,” says psychology professor Deirdre Barrett, Ph.D. “Some of it might just be nonsense.”

Hormonal changes, like those during pregnancy or the postpartum period, can also make your dreams crazy, as can some antihistamines and most antidepressants. (Both can be sedating, altering sleep patterns, and antidepressants change the brain’s chemistry.) A fever can also affect sleep and dreams, as can a stomachache, which is why some people believe spicy foods or eating right before bed causes wild dreams.

Why are certain dreams so common?

Falling from a cliff. Being chased. Flying. These themes persist across cultures and generations. “There’s folklore from almost every civilization showing that we all dream about these things,” says Cartwright. “They’re related to universal anxieties.” The predominant anxiety-dream themes express the fear of feeling humiliated, losing one’s beauty, not being desired, or not having the capabilities to succeed at something. They include:

Taking a test.

Finding yourself pregnant.

Forgetting your child someplace.

Appearing naked in public.

Standing onstage.

Teeth or hair falling out.

Being intimate with a stranger.