These non-self-experiments took place in the sleep laboratory at the NeuroBioPsychology at the University of Osnabrück. There were five subject, all students at the age between 20 and 25. They had mixed lucid dreaming experience (see Table ).


Total previous lucid dreams

Lucid dreams per month



















Table : Lucid dreaming experience of the pilot study's subjects

Before the first night, the participants were informed about the details of the experiments (see Appendix C). All subjects provided written informed consent. There was no monetary compensation for the study.

The participants answered one questionnaire before the first night, one after each night and one after each awakening from a dream (which was filled out in an interview-fashion by the experimenter).

All subjects were trained before the first night in decoding the relevant Morse code signals (i.e., the numbers from 0 to 9, “P” for plus and “M” for minus), first in theory and then in practice with 1000 Hz sinus tone stimuli (the same stimuli as were used in the experiment during the nights). They were also trained in signaling answer messages using eye movements to the left and to the right. They were informed to give the signal “look five times to the left (and in between back to center)” for signaling that they have a lucid dream. This signal is different to the left-right-left-right signal normally used in lucid dream research but was chosen in order to make it easier to detect in the Zeo EEG.

All subjects were asked to stay two consecutive nights in the sleep laboratory. Subject S3 offered to stay one additional night in the sleep laboratory. During all nights, the subjects wore the Zeo headband.

Subjects S3, S4 and S5 were additionally recorded with a polysomnographic device, a NeuroScan (amplifier and software) system, during their second (and for S3 also the third) night. This system recorded 19 channel EEG, horizontal and vertical EOG and chin EMG. Impedance was kept below 5 kΩ. Data was sampled at 500 Hz.

For REM sleep detection the same method as in the self-experiment was used. The same stimuli as in the self-experiment were used (computer generated 1000 Hz sinus tone). Again, a stimulus was played if out of the last 300 seconds, 50 % or more were classified as REM.

As written above, the “big” main aim of the experiments was to conduct a successful sleep communication. This includes: (1) The person to sleep communicate with has to be sleeping and dreaming, and this has to be detected by a dream sleep detector or by a body signal detector, (2) playback of a stimulus containing a message, possibly encoded using a coding scheme (here: a random math problem), (3) incorporation of the stimulus into the dream, (4) lucidity of the dreamer, (5) correct detection of the incorporated stimulus by the dreamer, (6) correct decoding of the stimulus message if a coding scheme is used, (7) comprehension of the message transported by the incorporated stimulus by the dreamer, (8) heeding the incorporated message by the dreamer and thinking about a response, (9) sending the response back to the wake world by encoding it into a body signal, and (10) correct detection and decoding of the body signal by hand or machine (here: an eye movement signal).

In order to enhance the chances for such a complete successful sleep communication, several sub-aims and their corresponding methods were defined for each of the two nights: During the first night of the experiment, one sub-goal was to find out the stimulus intensity at which the subject wakes up from REM sleep. Thus, the stimulus intensity (=loudness) was started at low level and then increased until the subject woke up. The wake-up intensity level was then noted. This had the additional effect that REM sleep during the first night was reduced. In previous studies it was shown that this REM sleep deprivation has no harmful effects on healthy humans (Vogel, 1975), but to have the effect of a REM sleep rebound in the following night, i.e. the “stolen” REM sleep is caught up on in the following night (Dement et al., 1966) which is of course beneficial for the sleep communication since more REM time means more time for trying to sleep communicate. Another sub-method of the first night was to record dream contents of the subjects in order to look out for recurring contents which might help the subject to become lucid during the second night.

In the second night, stimuli were played below the waking threshold determined during the first night. Additionally, subjects were woken up approximately 5 hours after going to bed in order to apply two lucid dream inducing techniques: wake-back-to-bed (WBTB) and mnemonic-induced-lucid-dreaming (MILD). WBTB means that the subject is waken up, held awake for approximately 20 to 30 minutes, and then goes back to bed. During this time awake, the subject was asked to rehearse the decoding and answering of the Morse coded math problems, to intensively think about the previously recorded dreams and to imagine how he could have become lucid during the dreams, and to go back to sleep with the intention: “The next time I dream, I will remember to recognize, that I am dreaming!” (MILD).

During both nights, the recording was stopped when the subject declared to not being able to fall sleep anymore.

The experimenter (the author of this thesis) was awake during all the nights.