Lucid dreamers can do maths equations while asleep, study reveals

Forget your basic sleep talking: Lucid dreamers can answer questions and even do MATHS while they’re asleep, study reveals

  • Experts asked questions like ‘what’s eight minus six’ as people had lucid dreams
  • A lucid dream is one in which you know you’re dreaming while you’re still asleep 
  • Dreamers answered correctly in real time with eye movements or facial muscles

From snoring to sleep walking, many of us do rather unusual things while we’re asleep. 

Now, a new study has revealed that some people are ‘lucid dreamers’, and can answer questions and even do maths while they’re snoozing.   

Researchers in the US asked lucid dreamers maths problems, such as ‘what’s eight minus six’, and yes-no questions, like ‘do you speak Spanish?’ 

Lucid dreams are when people experience a state of heightened awareness during sleep that allows them to recognise the dream and control what happens within it. 

In the experiments, dreamers answered correctly in real time with eye movements or facial muscle signals, demonstrating what’s called ‘interactive dreaming’. 

The experiments are promising for real-time communications when we’re asleep, which could help scientists adequately explain the phenomenon that is dreaming.  

Graphical abstract of the research experiments. Konkoly et al. show that individuals in REM sleep can perceive and answer an experimenter’s questions, allowing for real-time communication about a dream


One way to tackle nightmares is to become conscious, so you can wake yourself up or even banish your dream foes. 

This is known as lucid dreaming. 

When people lucid dream they become aware they are dreaming and can take some control over the ‘plot’ of their dreams, letting them have psychedelic adventures. 

A 2017 study identified three tricks that can increase your chances of having lucid dreams:

1. Reality testing – Check your environment several times a day to see whether or not you’re dreaming

2. ‘Wake back to bed’ – Wake up after five hours, stay awake for a short period, then go back to sleep in order to enter a REM sleep period, in which dreams are more likely to occur

3. MILD (mnemonic induction of lucid dreams) – Wake up after five hours of sleep and then develop the intention to remember that you are dreaming before returning to sleep, by repeating the phrase: ‘The next time I’m dreaming, I will remember that I’m dreaming.’ 

At the same time, imagine yourself in a lucid dream.

Read more: How to control your dreams 

Researchers tested the participants during rapid eye movement (REM) sleep, the deepest stage of sleep when lucid dreams occur.   

‘We found that individuals in REM sleep can interact with an experimenter and engage in real-time communication,’ said senior study author Ken Paller, a professor at Northwestern University. 

‘We also showed that dreamers are capable of comprehending questions, engaging in working-memory operations and producing answers.’

‘Most people might predict that this would not be possible – that people would either wake up when asked a question or fail to answer, and certainly not comprehend a question without misconstruing it.’

Scientific investigations of dreaming have been hampered by the delay between a dream and when people report on their dream – leading to forgotten details. 

‘There is considerable ambiguity about the experiences that may have transpired during a dream, based on retrospective reporting, and as well as about exactly when these experiences happened,’ the team say in their paper, published today in Current Biology. 

‘The ability to communicate with dreamers in real time, such that they could describe their experiences while in the midst of a dream, would greatly expand the possibilities for scientifically exploring dream experiences.’  

The researchers studied 36 people who aimed to have a lucid dream, across four independently conducted experiments with different approaches.  

In addition to the group at Northwestern University in the US, one group conducted studies at Sorbonne University in France, another at Osnabrück University in Germany and the other at Radboud University Medical Center in the Netherlands.

‘We put the results together because we felt that the combination of results from four different labs using different approaches most convincingly attests to the reality of this phenomenon of two-way communication,’ said first author Karen Konkoly at Northwestern University. 

‘In this way, we see that different means can be used to communicate.’

Common across all four institutions, however, was the use of electroencephalography (EEG), a method of recording electrical activity of the brain that involves electrodes placed along the scalp. 

Sleeping participants were asked questions in a variety of ways – not just verbally via audio recordings, but through tactile stimuli and flashing lights. 

This photo shows one of the study authors, Christopher Y. Mazurek at Northwestern University, in a full EEG rig just before a sleep session in the lab. The electrodes seen here on his face detect movement of the eyes during sleep

For example, one participant was stimulated during REM sleep with red and green LED light flashes to convey Morse-coded maths problems. 

Meanwhile, the answers from the dreamer were performed entirely from facial signals, not verbally, Professor Paller said.

This is because during REM sleep (and lucid dreaming) we experience what’s called atonia – a temporary paralysis of our arms and legs to prevent us from physically acting out our dreams. 

‘We needed to use physiological recordings in order for dreamers to communicate information to experimenters,’ he told MailOnline.

Illustration shows how the study participants responded to the questions heard as they dreamt. Eye movements from left to right answered maths questions, while facial muscle contractions as if smiling answered yes-no questions

‘Because REM sleep generally involves the phenomenon of muscle atonia throughout the body, speaking is not possible. 

‘Eye movements remain possible, and small muscle twitches can be recorded in some cases.’

Number of left-to-right eye movements corresponded to maths answers (so two movements from left to right for eight minus six, for example) while facial muscles corresponded to the yes-no questions.

For the latter, smiling (contraction of the zygomatic muscles) twice signalled ‘yes’ and furrowing the brow (contraction of the corrugator muscles) twice signalled ‘no’. 

This photo shows first author Karen Konkoly at Northwestern University watching brain signals from a sleeping participant in the lab. Researchers are working to expand and refine two-way communications with sleeping people so more complex conversations may one day be possible

One of the individuals, a 20-year-old Frenchman who succeeded with two-way communication, had narcolepsy and frequent lucid dreams. 

Among the others, some had lots of experience in lucid dreaming and others did not. 

Overall, the researchers found that it was possible for people while dreaming to follow instructions, do simple maths, answer yes-or-no questions or tell the difference between different sensory stimuli.  

After being awoken, the participants submitted dream reports of their experiences, which ranged from simple settings like a party to fighting with goblins in a faraway world. 

One said: ‘In my dream, I was at a party and I heard you asking questions. I heard your voice as if you were a God. 

‘Your voice was coming from the outside, just like a narrator of a movie. 

I heard you asking whether I like chocolate, whether I was studying biology, and whether I speak Spanish. 

‘I wasn’t sure how to answer the last one, because I am not fluent in Spanish, but I have some notions. 

‘In the end, I decided to answer ‘no’ and went back to the party.’ 

The study shows that individuals in REM sleep can perceive and answer an experimenter’s questions, allowing for real-time communication about a dream. 

Researchers are working to expand and refine two-way communications with sleeping people so more complex conversations may one day be possible. 

Finding a means to communicate could open the door in future investigations to learn more about dreams, memory, and how memory storage depends on sleep, the researchers say.

‘Our experimental goal is akin to finding a way to talk with an astronaut who is on another world, but in this case the world is entirely fabricated on the basis of memories stored in the brain,’ the researchers say in their paper.                            


Sleep is generally separated in four stages. The first three of these are known as ‘non rapid eye movement’ or NREM sleep.

The last stage is known as rapid eye movement or REM sleep. 

A typical night’s sleep goes back and forth between the stages. 

Stage 1: In the first five minutes or so after dropping off we are not deeply asleep. 

We are still aware of our surroundings but our muscles start to relax, the heart beat slows down and brainwave patterns, known as theta waves, become irregular but rapid.  

Although we are asleep during Stage 1, we may wake up from it feeling like we didn’t sleep at all.  

After around five minutes our bodies move into stage two.

Stage 2: This is when we have drifted into sleep, and if awakened would know you we been asleep. Waking up is still fairly easy.

This stage is identified by short bursts of electrical activity in the brain known as spindles, and larger waves known as K-complexes, which indicate that the brain is still aware of what is going on around it before turning off to a sub-conscious level.  

Heartbeat and breathing is slow, and muscles relax even further. 

Our body temperature drops and eye movements stop. 

Brain wave activity slows but is marked by brief bursts of electrical activity. 

Stage 3: Stage 3 non-REM sleep is the period of deep sleep that we need to feel refreshed in the morning. 

It occurs in longer periods during the first half of the night. 

Our heartbeat and breathing slow to their lowest levels during sleep and brain waves become even slower.

Our muscles are relaxed and it people may find it difficult to awaken us. 

The body repairs muscles and tissues, stimulates growth and development, boosts immune function, and builds up energy for the next day. 

Hypnagogia – the transitional state between wakefulness and sleep – is associated with NREM stages one to three.

Mental phenomena during hypnagogia include lucid thought, lucid dreaming, hallucinations and sleep paralysis. 

REM sleep:  REM sleep first occurs about 90 minutes after falling asleep. 

Our eyes move rapidly from side to side behind closed eyelids. 

Mixed frequency brain wave activity becomes closer to that seen in wakefulness. 

Our breathing becomes faster and irregular, and heart rate and blood pressure increase to near waking levels. 

Most dreaming occurs during REM sleep, although some can also occur in non-REM sleep. 

Arm and leg muscles become temporarily paralysed, which prevents us from acting out our dreams. 

As we age, we sleep less of your time in REM sleep. 

Memory consolidation most likely requires both non-REM and REM sleep.  

Source: US National Institutes of Health 

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