"Light works as if it’s a drug, except it’s not a drug at all."

-George C. Brainard, PhD, director of the Light Research Program at  Thomas Jefferson University in The New York Times (2011)

LED Lighting, Screens and Health

More Screen Sensitivity Literature

Cybersickness in the scientific literature

Cybersickness, reviewed in Stanney et al., 2020, is described as a condition mimicking classic motion sickness that is associated with using virtual reality (VR) or augmented reality (AR) technologies. Symptoms include "nausea, disorientation, oculomotor disturbances, drowsiness (a.k.a sopite syndrome) and other discomforts" (Stanney et al., 2020). Symptoms that may linger long after the VR or AR experience "can compromise postural stability, hand-eye coordination, visual functioning, and general well-being" (Stanney et al., 2020). Most of the population is susceptible to cybersickness (Stanney et al., 2020), although motion sickness susceptibility can vary over a 10,000-fold range in different people (reviewed in Lackner, 2014). The cause of cybersickness is unknown, with over ten proposed hypotheses (Stanney et al., 2020), including the hypothesis that cybersickness results from sensory discordance - disagreement in how the eyes, ears, and body perceive motion (discordance of visual, vestibular, and proprioceptive sensing of motion, respectively). Most research has focused on determining strategies for avoiding inducing cybersickness in VR and AR, although modern systems still induce cybersickness and research demonstrating that current technology is an improvement on previous generations is lacking (Stanney et al., 2020). NASA and the US military have interests in work on VR and AR, including the mitigation of cybersickness (Stanney et al., 2020). In a similar scenario, the use of night vision goggles when flying has been reported to cause migraine headache, spatial disorientation, and balance issues in a military helicopter pilot (Cho et al., 1995). While viewing the night vision display screen itself could be problematic, it's also possible that the rotating helicopter blades could be an enhanced source of flicker on the night vision display.

Requirements for VR or AR use for training or performance of one's job could prevent individuals susceptible to cybersickness from undertaking some careers.

"We would argue that the magnitude of this cybersickness problem, and its implications to job performance and career progression, are poorly understood by society in general. This is not only due to problems with existing hardware, which are likely to be resolved, but with a lack of understanding of how cybersickness manifests, varies across individuals, and how it may be mitigated. This lack of understanding has resulted in a deemphasizing of the importance of cybersickness research being conducted, and rather a push for cybersickness as being something users will eventually just adapt to"  (Stanney et al., 2020).

Stanney et al., 2020 provide an updated proposal for research and development priorities that are urgently needed and critically important to eliminate cybersickness.

Also see notes in Anecdotal reports of LED sensitivity and in Background: LED Screens on the use of  flicker as a strategy to reduce screen blur effects that may contribute to cybersickness.

"Cybersickness" has also been suggested in anecdotal reports (see Anecdotal reports of LED sensitivity) as the explanation for adverse health effects experienced by users of normal screens like cell phones and tablets. 

Cho AA, Clark JB, Rupert AH. Visually triggered migraine headaches affect spatial orientation and balance in a helicopter pilot. Aviat Space Environ Med. 1995 Apr;66(4):353-8. 

Lackner, J. R. Motion sickness: More than nausea and vomiting. Experimental Brain Research, 232 (2014) 2493–2510. https://dx.doi.org/10.1007%2Fs00221-014-4008-8

Stanney, K. et al. Identifying causes of and solutions for cybersickness in immersive technology: Reformulation of a research and development agenda. International Journal of Human-Computer Interaction, 36 (2020) 1783-1803. https://doi.org/10.1080/10447318.2020.1828535

Could screen flicker contribute to Zoom fatigue?

As increased videoconferencing during the COVID-19 pandemic led to widespread reports of "Zoom fatigue," scientists hypothesized that various psychological stress factors could lead to both physical and mental fatigue (Bailenson, 2020).  A Zoom Exhaustion & Fatigue Scale questionnaire (Fauville et al., Feb. 2020) assessed general physical or mental fatigue, vision blurriness, eye pain or irritation, and mental fatigue or irritability in social, motivational, and emotional areas. This questionnaire was distributed to thousands of individuals along with an open-ended question, questions addressing the psychological experience during a videoconference, and a question set assessing personality. There was a correlation among the general, visual/eye, emotional, motivational, and social fatigue scores that correlated with the amount of time spent in videoconferences, with women scoring higher than men (Fauville et al., April 2020). Several psychological factors helped to explain why videoconferences can be stressful. 

While the Zoom study focuses on psychological factors contributing to Zoom fatigue, it does not assess or rule out the possibility that there could also be a physiological cause of symptoms, at least for a subset of individuals or as a contributing factor more broadly. It is interesting that many of the symptoms assessed in the Zoom study are also among the symptoms reported by individuals who are more generally sensitive to LED lights and/or screens, such as physical fatigue, vision blurriness, eye pain/irritation, irritability, and descriptions of mental fatigue that suggest feeling anxiety. The "mental fatigue" that is reported in Zoom fatigue could overlap with the concentration and short-term memory problems reported by individuals who are sensitive to LED lights and/or screens. Since the Zoom video feed can be a source of visible screen flicker (see Background: LED Screens), and given the known health effects of visible flicker (see Flicker below 100 Hz) it would be interesting to assess to what degree that flicker, as well as the flicker associated with any increase in screen use overall, contributes to Zoom fatigue symptoms. It would also be interesting to assess other physical symptoms such as headache.

Bailenson, J. Why Zoom Meetings Can Exhaust Us. Wall Street Journal, April 3, 2020. https://www.wsj.com/articles/why-zoom-meetings-can-exhaust-us-11585953336

Fauville, et al. Nonverbal Mechanism Predict Zoom Fatigue and Explain Why Women Experience Higher Levels Than Men. SSRN Electronic Journal. April 14, 2021. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3820035#

Fauville, et al. Zoom Exhaustion & Fatigue Scale. SSRN Electronic Journal. February 23, 2021. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3786329