Stroboscopic Light Stimulation Safety Within and Beyond Laboratory Settings: Observational Evidence and Practical Guidance

Stroboscopic light stimulation (SLS) on closed eyes reliably evokes vivid geometric visual phenomena, and in some contexts, altered-state experiences, leading to its increasing use across research, public installations, recreational use, and exploratory clinical contexts. The main clinical risk for SLS is a photosensitive epileptic response. In contrast, non-epileptic sensitivities (e.g., migraine/photophobia, anxiety, autism/ADHD, psychosis) typically induce discomfort or distress rather than convulsive events. Here, we integrate a multi-laboratory safety survey of 1,070 participants, operational data from two commercial SLS providers, and a focused review of SLS and sensory-intolerance evidence. This synthesis was used to refine safety screening and to characterise adverse events. Across laboratory studies, 20 minor side effects (e.g., early withdrawal due to discomfort; ~18.7 per 1,000) were reported, with no severe incidents requiring medical attention. From two commercial datasets (~4.2 million closed-eye SLS sessions), 14 major adverse events requiring medical attention were documented (~3.3 per million); minor reactions were not systematically captured. Synthesising these strands, we developed the evidence-based Sussex Strobe Safety Screening Questionnaire (4SQ), which uses non-specialist language to identify known sensitivities to SLS, alongside practical recommendations for risk mitigation across research, clinical, commercial, and public contexts. Together, these findings suggest that the absolute risk under SLS is low but non-zero. Screening tools can help exclude pre-existing conditions, while graded exposure (e.g., a short 'taster' session, after which participants may opt out) and trained staff can mitigate the risk of first-episode events. Nonetheless, such events should be anticipated and minimised through clear screening pathways and managed through rehearsed on-site response plans.