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she adds that it is also possible that dream-
ers perceived the inputs but paid little at-
tention and forgot before awakening. The
proportion of people who respond could
potentially be improved with more train-
ing or by presenting questions when indi-
viduals are in specific sleeping brain states,
Konkoly says.
After establishing successful two-way
communication, participants were woken
up and asked to recount their dreams. In
most cases, they could remember receiving
the experimenters’ questions while asleep;
in some cases, the questions appeared to
be coming from outside the dream, where-
as other times they were integrated into the
dream. (One participant reported that the
lights in their dream started flickering,
which they were able to recognize as the
Morse-coded math problem.)
There were instances, however, when
people either did not recall the interactions
or had a distorted account. For example,
there were trials in which individuals an-
swered a math problem correctly while
asleep but did not remember the question
correctly after waking up. These findings
were published in February 2021 in Cur-
rent Biology.The findings “challenge our ideas
about what sleep is,” says Benjamin Baird,
a researcher who studies dreams at the
University of Wisconsin–Madison and
was not involved in this study. Sleep has
classically been defined as unresponsive-
ness to external environmental stimuli—
and that feature is still typically part of
the definition today, Baird explains. “This
work pushes us to think carefully—re-
think, maybe—about some of those fun-
damental definitions about the nature of
sleep itself and what’s possible in sleep.”
This kind of two-way communication
with dreamers could be used as a tool to
better study dreams, according to Paller.
In particular, he says, the observation that
the responses some people gave during
dreams did not match their reports after
waking provides evidence that such real-
time techniques will help researchers
get more accurate accounts of dreams—
and address whether dreams play a use-
ful role in processes such as memory.
Paller and his colleagues also suggest this
technique could be used by people to en-
hance problem-solving and creativity, by
providing a new way to process content in
their dreams.“I really liked this study,” says Chris-
tine Blume, a sleep scientist at the Center
for Chronobiology in Basel, Switzerland,
who was not involved in this work. “The
ex tent to which information can be pro-
cessed and responded to surprised me.”
But she adds that it is important to keep
in mind that the findings relate specifical-
ly to lucid dreaming, which is a special
type of dreaming that not many people
are able to experience.
Blume notes that even with lucid
dreamers, in most trials, the researchers
were not able to establish communication.
Therefore, how applicable this technique
would be to learning or creativity remains
an open question, she says.
Paller and his colleagues are now ex-
ploring what other types of questions can
be asked during sleep, as well as other
ways of receiving messages from sleepers,
such as sniffing. “We are hopefully going
to get better at doing this kind of experi-
ment,” he observes. “Then [we can] ask
new questions about what’s happening
during dreams.”Diana Kwon is a freelance journalist who covers health and
the life sciences. She is based in Berlin.