You’re walking down a hazy road lined with antique streetlamps. The lights are glowing, faintly red, and splash pockets of color here and there along your path. The color begins to crawl out from under its given lamppost and all of the scenery becomes imbued, brushed in a singular hue of translucent rouge. Suddenly, you’re startled by a gruff voice from behind—oh, a German Shepherd, sitting at your feet. He speaks to you in a rhythmic bark ... A rhythmic bark. You awaken to the sound of the alarm clock and the sight of the warm morning sunlight.
It’s not unusual to realize upon awakening that elements of our true physical surroundings have been incorporated into our dreams. Though we normally consider sleep to be a time when we are completely cut off from the real world, in fact, there continues to be a flow of input from our sensory systems, which may be fluidly incorporated into a dream. Of course, a strong enough stimulus would lead to an awakening, a fact that most of us take for granted when relying on an alarm clock.
Research on external incorporation into dreams has explored the influences of several different sensory systems, including touch, sight, and smell, on our nightly creations. Tactile experiments show that both pressure and temperature can influence the content of a dream. In a study conducted by Nielsen (1993), participants wore a pressure cuff on their leg while sleeping in the laboratory. During REM sleep, experimenters inflated the cuff to produce pressure on the leg and subsequently awoke participants for dream reports. The authors found several examples of leg pressure incorporated into dreams, sometimes in a subtle yet direct fashion (ie, tingling in the leg), and sometimes in a more elaborate fashion (ie, a dream sequence that involved paralysis of the leg, attempts to move the leg resulting in intense discomfort). Thus the physical sensation of pressure on the leg was incorporated in idiosyncratic ways, perhaps depending on the prior narrative of the dream or the quality of sleep.
In another niche of the dream field, researchers have made use of sensory stimuli as a tool for increasing lucidity. Many of the sleep masks marketed for lucid dreaming rely on blinking red lights that flash during REM sleep; these red lights appear within the dream, and clue the dreamer into the fact that they are actually sleeping. Successful users report seeing flashes of light in their dreams, for example “I was walking along a road with my boss and the whole scene flashed, cueing me that I was dreaming. I mentioned it to him, and flew a little to prove it” (subject dream report in LaBerge & Levitan, 1995). In this case, the users rely on a premeditated cue to trigger lucidity. Conceivably, other sensory signals, such as the pressure cuff, could similarly be used to induce lucid dreams.
One important question is just how much sensory stimuli is able to pierce through the barrier of sleep and into your dreams. Probably there are variations in sensitivity, similar to waking experience, where certain individuals are more aware of sensory quality and bodily sensation than others. An original project by Elizaveta Solomonova will explore sensory incorporations in the dreams of Vipassana meditators, a technique that focuses on awareness of body sensations. Funded by Mind and Life Institute, this project may reveal whether body-oriented contemplative practice alters embodied experience in dreams. In all cases, the impact of sensory stimuli on dreams suggests that the creation of dreams occurs as much in the body as it does in the mind, and underlines the role of the body in conscious experience.
LaBerge, S., & Levitan, L. (1995). Validity established of DreamLight cues for eliciting lucid dreaming. Dreaming, 5(3), 159-168.
Nielsen, T. A. (1993). Changes in the kinesthetic content of dreams following somatosensory stimulation of leg muscles during REM sleep. Dreaming, 3(2), 99-113.
Elizaveta Solomonova. University of Montreal. Embodied dreaming and procedural memory consolidation following daytime nap in Vipassana meditators and non-meditating controls: a neurophenomenological study. http://www.mindandlife.org/grants/varela-awards/varela-awardees/