Flickering Lights Can Trigger Altered States Of Consciousness Similar To Psychedelics


Ben Taub

Freelance Writer

clockJul 6 2021, 15:04 UTC

Flashing lights can cause hallucinations, the new study found. Image: Oleg Mikhaylov/

While psychedelic substances like psilocybin and ayahuasca are becoming increasingly popular due to their apparent mental health benefits, the use of such mind-altering compounds is certainly not for everybody. For this reason, researchers are keen to develop non-pharmacological techniques to induce psychedelic-like effects, and new research suggests that flickering lights may have the capacity to spark hallucinations similar to those produced by LSD and other drugs.

In the study published in the journal PLOS ONE, the authors point out that early psychedelic studies conducted in the 1960s used flickering lights to enhance the effects of mescaline and magic mushrooms, and that similar methods involving flashing light arrays are sometimes used recreationally to generate altered states of consciousness. They decided to investigate whether the practice has the capacity to trigger the neuronal mechanisms underlying the effects of psychedelics, with a view to creating novel mental health therapies without relying on the use of drugs.


A total of 24 participants were recruited to take part in the small study, each of whom was first screened for indications of photosensitive epilepsy before beginning the trial. Once cleared, volunteers were placed in a dark room and instructed to close their eyes while a stroboscopic light flickered on and off for a period of 20 minutes.

In order to compare the effects of this method with those of pharmacological psychedelics, the researchers employed a series of scientifically validated questionnaires that are typically used to measure altered states of consciousness in studies involving drugs. In doing so, they found that flickering lights generate a degree of “vigilance reduction” – which refers to the experience of “clouded consciousness” – that is comparable to a low dose of ketamine.

Furthermore, participants reported seeing “elemental imagery” hallucinations, consisting of “colorful, dynamically changing fractal structures,” that were similar in strength to those typically produced by an average recreational dose of LSD.  

Summing up this finding, the study authors state that “our results demonstrate that the visual effects of flickering light stimulation, in some aspects, are rated to be similarly strong as the effects induced by certain psychedelic substances.” However, they go on to explain that “the induced spectrum of phenomena is rather limited to visual effects, while other aspects of alterations in consciousness are less robustly induced.”


For example, the use of flickering lights did not precipitate any of the “ego dissolution or mystical-type experiences” that are commonly reported by users of psychedelics, while complex hallucinatory visions featuring “meaningful objects” were also lacking.

Furthermore, recent studies have indicated that psychedelic drugs have the capacity to enhance users’ creative thinking abilities, although participants in this study demonstrated no such increases in creativity after being exposed to flickering lights.

Nonetheless, the study authors conclude that “flicker light stimulation is capable of inducing visual effects with an intensity rated to be similar in strength to effects induced by psychedelic substances and thereby support the investigation of potentially shared underlying neuronal mechanisms.”

 This Week in IFLScience

Receive our biggest science stories to your inbox weekly!

  • tag
  • psychedelics