"The concept of Snoezelen was defined in the late 1970's by two Dutch therapists, Jan Hulsegge and Ad Verheul. While working at the De Hartenberg Institute in Holland, a center for people with intellectual disabilities, the two therapists learned of the positive responses a colleague was able to elicit from his severely challenged clients while exposed to a sensory environment he had assembled. Hulsegge and Verheul set up an experimental sensory tent at their annual summer fair to further test the idea. Constructed simply as a roof on poles with plastic sheeting dividers, this first sensory tent was filled with simple effects such as a fan blowing shards of paper, ink mixed with water and projected onto a screen, musical instruments, tactile objects, scent bottles, soaps, and flavorful foods. It was a tremendous success, especially with low-functioning clients who demonstrated positive verbal and nonverbal feedback. The following year, they built another creation with a concept name: "Snoezelen", a contraction of "snuffelen" (to explore) and "doezelen" (to relax). News of the successful experiments quickly generated interest across Europe and therapists began creating permanent and semi-permanent "Snoezelen" rooms at their centers." 
"Another landmark Snoezelen centre was installed in 1987 at Whittington Hall, a large institution for adults with intellectual disabilities located in North Derbyshire, U.K. Joe Kewin, a senior manager and his team offered six sensory environments to their clients and also pioneered early research examining client response to the Snoezelen multisensory approach. The results were impressive, specifically in clients who showed a marked reduction in self-abusive behaviors. Snoezelen is now used widely in education and care settings for children with disabilities and autism spectrum disorders. Encouraging results have also been shown from people suffering from mental illness, chronic pain, acquired brain injury, and stress. Over the past fifteen years, Snoezelen has expanded into 30 countries with thousands of installations, a worldwide foundation, national and international conferences, and research projects." 
"Ideally, snoezelen is a non-directive therapy and can be staged to provide a multi-sensory experience or single sensory focus, simply by adapting the lighting, atmosphere, sounds, and textures to the specific needs of the client at the time of use. There is no formal focus on therapeutic outcome - the focus is to assist users to gain the maximum pleasure from the activity in which they and the enabler are involved. An advantage of snoezelen is that it does not rely on verbal communication and may be beneficial for people with profound autism, as it may provide stimulation for those who would otherwise be almost impossible to reach.
Snoezelen is used for people with autism and other developmental disabilities, dementia, and brain injury. However, research on the benefits of treatment is scarce, based on variable clinical study designs.
A small research study carried out in Brussels compared the behavior of nine adult clients with profound autism in both classroom and Snoezelen settings. Though individual results varied, the study claimed a 50% reduction in distress and stereotypical behavior, and seventy-five percent less aggression and self-injury in the Snoezelen environment." 
ALL IMAGES OF SNOEZELEN ENVIRONMENTS TAKEN FROM VARIOUS SOURCES, CITED VIA CLICK-THROUGH LINK; TEXT TAKEN FROM OMNISPACE.ORG , AND FROM WIKIPEDIA ; MORE SNOEZELEN GALLERIES ARE AVAILABLE HERE; MORE INFORMATION ON SNOEZELEN THERAPY AVAILABLE HERE AND HERE