An oneirogen, from the Greek ὄνειρος óneiros meaning "dream" and gen "to create", is that which produces or enhances dream-like states of consciousness. This is characterized by an immersive dream state similar to REM sleep, which can range from realistic to alien or abstract. Many dream-enhancing plants such as dream herb (Calea zacatechichi) and African dream herb (Entada rheedii), as well as the hallucinogenic diviner's sage (Salvia divinorum), have been used for thousands of years in a form of divination through dreams, called oneiromancy, in which practitioners seek to receive psychic or prophetic information during dream states. The term oneirogen commonly describes a wide array of psychoactive plants and chemicals ranging from normal dream enhancers to intense dissociative or deliriant drugs. Effects experienced with the use of oneirogens may include microsleep, hypnagogia, fugue states, rapid eye movement sleep (REM), hypnic jerks, lucid dreams, and out-of-body experiences. Some oneirogenic substances are said to have little to no effect on waking consciousness, and will not exhibit their effects until the user falls into a natural sleep state.
Dimethyltryptamine can trigger intensely vivid and surreal spiritually charged dream states.
Diphenhydramine ("Benadryl") can invoke an intense hypnagogic REM-like microsleep often indifferentiable from reality. Deliriants can therefore be considered to trigger an oneirogenic state by blocking acetylcholine and suppressing cholinergic system activity.
Amphetamine and other stimulants can create psychotic episodes which may be defined as bursts of dream activity erupting spontaneously into waking states; this is not due to the substance itself but rather a result of the prolonged suppression of cholinergic activity and REM sleep due to amphetamine or stimulant abuse.
Somnium (album) is a 7 1/2 hour long soundscape designed to maximize dreaming when played during sleep.
Valerian (herb) - A study conducted in the UK in 2001 showed that valerian root significantly improved stress induced insomnia, but as a side effect greatly increased the vividness of dreams. This study concluded that valerian root affects REM due to natural chemicals and essential oils that stimulate serotonin and opioid receptors.
Water Lily dried flowers may be smoked, or the rhizomes eaten, to promote vivid dreams.
Wild Red Asparagus root may promote dreams that involve flying.