Science has made great progress in
deepening our understanding of dreaming.
Still, there is no answer to the question:
Why do we dream?
Since the earliest of recorded histories,
people have theorized about the function and
meaning of dreams. Answers came largely
from the spirit world until Aristotle and
Plato developed the drive related hypothesis
that was later expanded on by the European
psychoanalysts of the 19th and 20th centuries.
This hypothesis defines dreaming as a way to
act out unconscious desires in a safe or “unreal”
setting, presumably because to do so in reality
would be unacceptable or even detrimental.
But even in the 21st century we still are not
sure why we dream. The only way to study
dreams is to ask the dreamer.
However, one thing we know for sure
is that dreaming is something that the vast
majority of humans do every night of their lives.
There are, however, a great number of theories
being explored. While some scientists posit that
dreaming has no direct function—but instead
is a consequence of other biological processes
that occur during sleep—many studying sleep
and dreams believe dreaming serves a primary
purpose. Theories of dreaming span scientific
disciplines, from psychiatry and psychology to
neurobiology. Some current theories suggest
that dreaming is:
• The brain responding to biochemical changes
and electrical impulses that occur during sleep.
• A form of consciousness that unites past,
present and future in processing information
from the first two, and preparing for the third.
• A protective act by the brain to prepare
itself to face threats, dangers and challenges.
There is not likely ever to be a simple answer,
or a single theory that explains the full role of
dreaming to human life. Biological, cognitive,
psychological—it’s very likely that dreaming
may serve important functions in each of
these realms.
Like sleep, dreams are vulnerable
to disruption from problems with mental
and physical health. There are a number of
conditions (as well as medications) that may
affect dreams, and that can make dreams more
difficult and disturbing.
Depression and anxiety often are accompanied
by nightmares, and the presence of nightmares
may be an indication of the severity of
depression. Research has found that among
patients with Major Depressive Disorder, the
presence of frequent nightmares is associated
with suicidal tendencies. People who are
depressed or anxious are more likely to have
stressful, disturbing, or frightening dreams,
sometimes in the form of recurring dreams.
There’s evidence that one type of
drug commonly used to treat depression may
alter dreaming. Selective Serotonin Uptake
Inhibitors (SSRI) appear to affect dreaming
in several ways. SSRI may decrease dream
recall—the ability to remember dreams. This
type of drug may intensify dreaming. SSRI
may also lead to the presence of more positive
• A component and form of memory
processing, aiding in the consolidation of
learning and short-term memory to long-term
memory storage.
• An extension of waking consciousness,
reflecting the experiences of waking life.
• A means by which the mind works through
difficult, complicated, unsettling thoughts,
emotions, and experiences, to achieve
psychological and emotional balance.
2
on the other hand, may lead to nightmares and
may also intensify dreaming.
Drugs and alcohol also can affect
dreaming. Alcohol disrupts the normal, healthy
sleep cycle and leads to fragmented sleep.
Consuming alcohol heavily and too close to
bedtime may alter and diminish time spent
in REM sleep. Studies show that alcohol-
dependency is linked to dreams with more
negative emotional content. Marijuana also
disrupts and reduces REM sleep. Withdrawal
from marijuana and cocaine has been shown
in studies to induce strange dreams. Certain
sleep disorders may be accompanied by altered
dreaming. Insomnia can heighten dream recall,
and also lead to more stressful and disturbing
dreams. (Depression and anxiety are also more
likely in people with insomnia.)
Obstructive sleep apnea, because of its
ability to disrupt normal REM sleep, can cause
disturbed dreaming with more bizarre and
negative dream content. Narcolepsy, a disorder
that involves extreme daytime tiredness and
altered sleep-wake cycles, can also lead to
more negative and bizarre dreams. Restless
Leg Syndrome, a neurological disorder and a
sleep disorder, can also be accompanied by
nightmares. REM behavior disorder (RBD)
is a condition where the normal paralysis that
occurs during REM sleep doesn’t take place.
People with REM behavior disorder can move
during this sleep phase, and often act out
physically in reaction to their dreams.
This activity can be violent—thrashing,
kicking, getting out of bed—and can lead to
injury to the sleeper or a bed partner. We
don’t know precisely what causes RBD, but
it is associated with neurological illness and
injury, as well as to withdrawal from alcohol
or narcotics, or use of some anti-depressants.
Nightmares and disturbed dreaming are a
hallmark of post-traumatic stress disorder
(PTSD), as is disrupted sleep. People who
suffer from PTSD often experience frequent
and recurring nightmares, which may be
accompanied by acting out during dreams,
with symptoms similar to REM behavior
disorder. PTSD occurs in some people who’ve
experienced forms of trauma, including assault,
disaster, war and combat. Soldiers who’ve
served in active combat often experience sleep
problems and disordered dreaming linked to
trauma and PTSD. After years of observing a
particular group of symptoms among combat
soldiers, sleep scientists are now proposing
the creation of a new sleep disorder: Trauma
Associated Sleep Disorder, with symptoms that
incl