"What is the physiology of dreams and lucid dreams?"


The electrical activity of the brain has been observed and classified with EEG (electroencephalograph) equipment; signals are picked up from the scalp by electrodes, then filtered and amplified to drive a graph recorder. Brain activity has been found to produce specific ranges for certain basic states of consciousness, as indicated in 'Hz' (Hertz, or cycles/vibrations per second):

  • delta -- 0.2 to 3.5 Hz (deep sleep, trance state)
  • theta -- 3.5 to 7.5 Hz (day dreaming, memory)
  • alpha -- 7.5 to 13 Hz (tranquility, heightened awareness, meditation)
  • beta -- 13 to 28 Hz (tension, 'normal' consciousness)
  • In the drowsy state before falling asleep, the EEG is characterized by many alpha waves while the muscles start to relax. Gradually this state gives way to Stage 1 sleep. Three more stages follow, each having different EEG patterns and marked by successively deeper states of relaxation. By Stage 4 the sleeper is very relaxed, his breathing is slower, and skin resistance high. He is very hard to wake up. If the dreamer is awakened, he may say that he was thinking about something or he may describe some vague imagery, but he will rarely recount anything which sounds like a typical dream.

    But this is not all there is to sleep -- increasing oblivion. In a normal night's sleep, a distinct change takes place an hour or two after the onset of sleep. Although the muscles are still relaxed, the sleeper may move, and from the EEG it appears that he is going to wake up and he returns to something resembling Stage 1 sleep. Yet he will still be very hard to wake up, and in this sense is fast asleep. The most distinctive feature, however, is the rapid eye movements, or REMs and the stage is also called REM-sleep. In earlier stages the eyes may roll about slowly, now, however, they dart about as though watching something. If woken up now the sleeper will usually report that he was dreaming.

    Lucid dreams implied that there could be consciousness during sleep, a claim many psychologists denied for more than 50 years. Orthodox sleep researchers argued that lucid dreams could not possibly be real dreams. If the accounts were valid, then the experiences must have occurred during brief moments of wakefulness or in the transition between waking and sleeping, not in the kind of deep sleep in which REMs and ordinary dreams usually occur. In other words, they could not really be dreams at all.

    This contention presented a challenge to lucid dreamers who wanted to convince people that they really were awake in their dreams. But of course when you are deep asleep and dreaming you cannot shout, 'Hey! Listen to me. I'm dreaming right now.' During REM sleep, the muscles of the body, excluding the eye muscles and those responsible for circulation and respiration, are immobilized by orders from a nerve center in the lower brain. This fact prevents us from acting out our dreams. Occasionally, this paralysis turns on or remains active while the person's mind is fully awake and aware of the world.

    It was Keith Hearne [Hea78], of the University of Hull, who first exploited the fact that not all the muscles are paralyzed. In REM sleep the eyes move. So perhaps a lucid dreamer could signal by moving the eyes in a predetermined pattern. Lucid dreamer Alan Worsley first managed to do this in Hearne's laboratory. He decided to move his eyes left and right eight times in succession whenever he became lucid. Using a polygraph, Hearne could watch the eye movements for sign of the special signal. The answer was unambiguous. All the lucid dreams occurred in definite REM sleep. In other words they were, in this sense, true dreams.

    A typical lucid dream lasted between two and five minutes, occurred at about 6.30 a.m., about 24 minutes into a REM period and towards the end of a 22-second REM burst. The nights on which lucid dreams occurred did not show a different sleep pattern from other nights, although they did tend to follow days of above average stimulation.

    It is sometimes said that discoveries in science happen when the time is right for them. It was one of those odd things that at just the same time, but unbeknownst to Hearne, Stephen LaBerge, at Stanford University in California, was trying the same experiment. He too succeeded, but resistance to the idea was very strong. In 1980, both Science and Nature rejected his first paper on the discovery [LaB85]. It was only later that it became clear just how important this discovery had been.

    Some conclusions can be drawn from this information. In both OBEs and lucid dreams, the person seems to have his waking consciousness, or something close to it. He is able to see clearly, but what he sees is not quite like the physical and it appears to have many of the properties of a dream world or imaginary world. But there are differences as well: the lucid dream starts more often when the subject is asleep, and the dream world is less distinct and real than the OB 'world,' allowing less control and freedom of movement; in addition, the person who has an OBE starting from the waking state never actually thinks he is dreaming. Most lucid dreams involve only the subject, but there are cases on record of 'meetings' in lucid dreams. The important question is whether the OBEer is observing the same world as the lucid dreamer. Are the two experiences essentially aspects of the same phenomenon?

    According to Stephen LaBerge it seems possible that at least some OBEs arise from the same conditions as sleep paralysis, and that these two terms may actually be naming two aspects of the same phenomenon [LL91]. In his opinion the survey evidence favors this theory. There is also considerable evidence that people who tend to have OBEs also tend to have lucid dreams, flying and falling dreams, and the ability to control their dreams [Bla84, Gli89, Irw88]. Because of the strong connection between OBEs and lucid dreaming, some researchers in the area have suggested that OBEs are a type of lucid dream [Far76, Hon79, Sal82].

    One problem with this argument is that although people who have OBEs are also likely to have lucid dreams, OBEs are far less frequent, and can happen to people who have never had lucid dreams. Furthermore, OBEs are quite plainly different from lucid dreams in that during a typical OBE the experient is convinced that the OBE is a real event happening in the physical world and not a dream, unlike a lucid dream, in which by definition the dreamer is certain that the event is a dream. There is an exception that connects the two experiences -- when we feel ourselves leaving the body, but also know that we are dreaming.

    LaBerge organized a study which consisted of analysis of the data of 107 lucid dreams from a total of 14 different people. The physiological information that was collected included brain waves, eye-movements and chin muscle activity. In all cases, the dreamer signaled the beginning of the lucid dream by making a distinct pattern of eye movements. After verifying that all the lucid dreams had eye signals showing that they had happened in REM sleep, they were classified into DILDs and WILDs, based on how long the dreamers had been in REM sleep without awakening before becoming lucid, and on their report of either having realized they were dreaming while involved in a dream (DILD) or having entered the dream directly from waking while retaining lucidity (WILD). Alongside the physiological analysis each dream report was scored for the presence of various events that are typical of OBEs, such as feelings of body distortion (including paralysis and vibrations), floating or flying, references to being aware of being in bed, being asleep or lying down, and the sensation of leaving the body.

    Ten of the 107 lucid dreams qualified as OBEs, because the dreamers reported feeling as if they had left their bodies in the dream. Twenty of the lucid dreams were WILDs, and 87 were DILDs. Five of the OBEs were WILDs (28%) and five were DILDs (6%). Thus, OBEs were more than four times more likely in WILDs than in DILDs. The three OBE-related events which were looked for also all occurred more often in WILDs than in DILDs. Almost one third of WILDs contained body distortions, and over a half of them included floating or flying or awareness of being in bed. This is in comparison to DILDs, of which less than one fifth involved body distortions, only one third included floating or flying, and one fifth contained awareness of bed.

    The reports from the five DILDs that were classified as OBEs were actually much like those from the WILD-OBEs. In both the dreamers felt themselves lying in bed and experiencing strange sensations including paralysis and floating out-of-body. Although these lucid dreams sound like WILDs, they were classified as DILDs because the physiological records showed no awakenings preceding lucidity. However, it is possible that these people could have momentarily become aware of their environments (and hence been 'awake') while continuing to show the brainwaves normally associated with REM sleep.

    The laboratory studies show that when OBEs happen in lucid dreams they happen either when a person re-enters REM sleep right after an awakening, or right after having become aware of being in bed. Could this relationship apply to OBEs and lucid dreams that people experience at home, in the 'real world'?

    Not being able to take the sleep lab to the homes of hundreds of people LaBerge conducted a survey about OBEs and other dream-related experiences. The difference between his survey and previous ones is that in addition to asking if people had had OBEs, he asked specifically about certain events that are known to be associated with WILDs, namely, lucid dreaming, returning directly to a dream after awakening from it, and sleep paralysis.

    A total of 572 people filled out the questionnaire. About a third of the group reported having had at least one OBE. Just over 80 percent had had lucid dreams. Sleep paralysis was reported by 37 percent and 85 percent had been able to return to a dream after awakening. People who reported more dream-related experiences also reported more OBEs. For example, of the 452 people claiming to have had lucid dreams, 39 percent also reported OBEs, whereas only 15 percent of those who did not claim lucid dreams said they had had OBEs. The group with the most people reporting OBEs (51%) were those who said they had experienced lucid dreams, dream return, and sleep paralysis.

    In this survey, people reporting frequent dream return also tended to report frequent lucid dreams. Thus, LaBerge believes that the fact that dream return frequency is linked with OBE frequency in this study gives further support to the laboratory research finding that WILDs were associated with OBEs. On the other hand he stresses that the proof that some or even most OBEs are dreams is not enough to allow us to say that a genuine OBE is impossible. However, he suggests that if you have an OBE, why not test to see if the OBE-world passes the reality test. Is the room you are in the one you are actually sleeping in? If you have left your body, where is it? Do things change when you are not looking at them (or when you are)? Can you read something twice and have it remain the same on both readings? LaBerge asks 'If any of your questions and investigations leave you doubting that you are in the physical world, is it not logical to believe you are dreaming?' [LL91].


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