Environmental culprits that trigger reactions, dysregulation, or physical sensitivity reactions are often overlooked and underestimated. Compact fluorescent light bulbs (“CFLs”) have become increasingly ubiquitous, as mental health-friendly incandescent bulbs are slowly being phased out in the U.S., Canada, and Europe. While proponents argue that they save energy costs,* if energy efficient bulbs increase mental and physical disease burden—even if by a small amount—the collective cost to public health to use them may be enormous.



regarding potentially harmful effects of CFLs is typically focused on the presence of neurotoxic mercury inside the bulb, the various forms of radiation emitted, “dirty electricity”, or the relatively high amounts of blue light causing sleep disturbance via melatonin suppression.1 But there appear to be other aspects that are concerning as well.

What About “Flicker”?

Any fluorescent bulb (tubes or CFLs) will emit a “flicker,” which can trigger nervous system events like migraines, tics, or seizures in sensitive individuals. Manufacturers now claim that any flicker present in newer bulbs is imperceptible to the human eye, and thus are considered flicker-free. But how do we know that the brain doesn’t get irritated by a flicker the eye can’t “see”? I myself am sensitive to overhead fluorescent lights as they bother my eyes and make me feel drained. And since I see patients with autism, tics, and seizure disorders, I have made a point to only use incandescent light in whichever office I’m working in, especially since several of my more sensitive patients have complained or asked me to turn them off on the days I’ve been forced to use them. patients may also report intolerance to fluorescent light.

CFLs, on the other hand, feel even worse to me than overhead fluorescents—I can barely stand to be in a room with one. They make me feel jittery, fragmented, and irritable. I realize they bother me more than most people, but nevertheless the experience has convinced me that the light produced by CFLs directly affects the nervous system. I felt that there had to be something about the light quality itself –not just the radiation or melatonin suppression—that irritate neurons (brain cells), either by electrical excitability (causing chaotic signaling in the brain) or by a general physiological stress (fight or flight) response—or both.



Fluorescent Light Induces a Stress Response

Sure enough, numerous studies point to light quality, color temperature, or certain spectral patterns inducing a stress response. Interestingly, the effects are non-visual, meaning they are caused by light signals that hit the eye’s retina but that do not travel from there to the visual cortex (where we perceive images), but rather to the circadian pathways.



Although the stress reaction from CFLs is likely caused by several factors, here are two separate mechanisms to consider.

The high color (colder/bluer) temperature of fluorescent light stimulates the non-visual pathways from the eye to various parts of the brain that involve biorhythms (e. . “the ”), stress hormones, emotions, arousal levels, and muscle tension.





According to a research summary of CFLs’ effect on stress reactions, the spectral composition from CFL bulbs does not just suppress melatonin, but directly triggers a fight or flight response via hormones, biorhythm disruption, and stimulation of the brain’s arousal center.**2 Research consistently demonstrates fluorescent lights raise stress markers, such as reduced heart rate variability, raised blood pressure, increased skin conductance, stronger startle response, reduced drop in body temperature during sleep, increased cortisol, and reduced slow wave (stage 4, the deepest stage) compared to full spectrum incandescent lighting.3 4 5 Since there is evidence that radiation and dirty electricity also induce stress reactions, the stress effect of CFLs is troublesome.



The emerging field of “physiological anthropology” focuses on the impact of technological environmental factors, such as the biological effects of artificial light so that we can make appropriate adjustments and improve quality-of-life. For example, one study found that dynamic light in a first grade classroom that changed depending on the students’ needs throughout the day improved oral reading fluency.6 Another study demonstrated increases in prosocial behavior in adults when exposed to warmer light, as measured by preference to resolve conflict with rather than avoidance, and by increased time spent doing unpaid volunteer work.7



Although full spectrum fluorescent lighting (FSFL) has been proposed as a solution to more closely mimic natural daylight, studies regarding its effects on mood and are inconsistent; one theory about the inconsistent effects are that FSFL may produce more flicker both in brightness (luminosity) and color (chromatic).8

Pupillary “flutter” caused by the spiked spectral pattern emitted by fluorescent light triggers aberrant signaling. This mechanism is more speculative, and if proven true may have a more pronounced effect in those individuals with autism or other neurological sensitivities/dysfunction. Because fluorescent light by nature emits spectral peaks (e.g. blue and red “bursts”) as the phosphorous fluoresces vs. the smooth and continuous full spectrum output of incandescent light,*** fluorescent light is more difficult for the eyes and brain to process. Thus, one hypothesis is that the spiked nature causes erratic pupil constriction, alternating between constriction with blue spectral spikes or bursts and relative dilation from red light bursts, which then agitates the brain.9



Support for this effect is the finding that individuals have a slower pupillary response to light,10 and this is one of the populations that are thought to be extra sensitive to fluorescents. Perhaps this slower pupil response causes a higher visual “load” when processing fluorescent light, which depletes mental resources and makes the individual more likely to be agitated, disruptive, , or to self-stimulate in an attempt to regulate the nervous system by blocking out the external environment.



Do Fluorescent Lights Trigger Disruptive Behavior?

Though the research on this subject is sparse, there have been a handful of studies that indicate increased repetitive behaviors (in autism)11 12 or hyperactivity13 when subjects are exposed to fluorescent vs. incandescent light. Message boards for parents of children with tics/Tourette’s often mention fluorescent lights—especially intense ones—triggering tics. It’s important to note that these studies looked at immediate or near-term effects; I suspect the long term effects, like those that occur from overstimulating screen-time, would be more pronounced as the dysfunction accumulates.

Let the Precautionary Principle Be Your Guide



The precautionary principle or precautionary approach states if an action or policy is associated with a suspected risk of causing harm to the public or to , that action can and should be taken to prevent such harm, even if the harm is not yet scientifically proven. Particularly with children, we should proceed with extreme caution, since children have unique vulnerabilities (for example to UV radiation), are still developing, and may not bear the full brunt of toxic exposures for decades. Furthermore, in light of rising rates of autism and other mental health issues in children, any and all environmental changes in recent decades should be looked at very closely.

The jury may be out regarding CFLs causing or exacerbating specific neurological or disorders or behaviors. But the evidence seems pretty solid that CFLs and other fluorescent lights induce a stress response and negatively impact sleep, which we know impacts , , appropriate immune responses, hormonal balance, and repair mechanisms.



The healthiest light is sunlight or candlelight, followed by incandescent, then halogen, then LEDs, then CFLs. I recommend that parents of children with psychiatric, neurological, learning, or chronic medical conditions switch out all CFLs in the home for incandescent or halogen bulbs. This is particularly important to do in and near your child’s bedroom. And since it’s likely your child’s classroom has overhead fluorescents—adding hours daily of exposure—ask that your child be allowed to sit next to a window, and if some of the overhead lights nearest the window can be turned off. Lastly, you can also help synchronize your child’s circadian rhythms by exposing him or her to bright natural light first thing in the mornings, which will not only improve sleep but will help buffer against any ill effects from artificial light.

For more about how light from electronic screen devices can cause nervous system dysregulation, visit www.drdunckley.com/videogames and check out Reset Your Child's Brain: A Four Week Plan to End Meltdowns, Raise Grades and Boost Social Skills by Reversing The Effects of Electronic Screen-Time.

*Why not simply reduce air conditioning use instead? How many of us take a sweater to the office even in the summer because it’s freezing??

** SCN=suprachiasmatic nuclei, PVN=periventricular nuclei, MFB=medial forebrain bundle, RF=reticular formation. I made a graphic to demonstrate this but could not add it: The technical version of this phenomenon is that light hits the retina, travels to the SCN which regulates circadian rhythms and melatonin. The signal then goes to the PVN which projects to both (hormones, including cortisol) and autonomic nervous system (fight-or-flight vs rest-and-digest balance) pathways. From the PVN, signals travel to the MFB, which is concerned with emotion and reward seeking, and the RF, which is the arousal center that projects "up" to the brain and "down" to the spinal cord, triggering muscle tension in the limbs.

*** Incandescent light is emitted in a smooth, symmetrical, sinusoidal wave, while CFLs create perturbances in the electricity via backflow as they transform energy to make it “efficient”.

1. Magda Havas, Health Concerns Associated with Energy Efficient Lighting and Their Electromagnetic Emissions, Scietific Committee on Emerging and Newly Indentified Health Risks (SCENIHR), (June 2008).

2. Akira Yasukouchi and Keita Ishibashi, “Non-Visual Effects of the Color Temperature of Fluorescent Lamps on Physiological Aspects in Humans,” Journal of Physiological Anthropology and Applied Human Science 24, no. 1 (January 2005): 41–43.

3. M. R. Basso, “Neurobiological Relationships Between Ambient Lighting and the Startle Response to Acoustic Stress in Humans,” International Journal of Neuroscience 110, no. 3–4 (January 1, 2001): 147–57, doi:10.3109/00207450108986542.

4. Tomoaki Kozaki et al., “Effect of Color Temperature of Light Sources on Slow-Wave Sleep,” Journal of Physiological Anthropology and Applied Human Science 24, no. 2 (March 2005): 183–86.

5. Yasukouchi and Ishibashi, “Non-Visual Effects of the Color Temperature of Fluorescent Lamps on Physiological Aspects in Humans.”

6. M. S. Mott et al., “Illuminating the Effects of Dynamic Lighting on Student Learning,” SAGE Open 2, no. 2 (June 1, 2012), doi:10.1177/2158244012445585.

7. Robert A. Baron, MarkS. Rea, and SusanG. Daniels, “Effects of Indoor Lighting (illuminance and Spectral Distribution) on the Performance of Cognitive Tasks and Interpersonal Behaviors: The Potential Mediating Role of Positive Affect,” and Emotion 16, no. 1 (March 1, 1992): 1–33, doi:10.1007/BF00996485.

8. J. A. Veitch and S. L. McColl, “A Critical Examination of Perceptual and Cognitive Effects Attributed to Full-Spectrum Fluorescent Lighting,” Ergonomics 44, no. 3 (February 20, 2001): 255–79, doi:10.1080/00140130121241.

9. “Fluorescent Lighting Flicker,” Seattle Community Network, accessed September 15, 2014, http://www.scn.org/autistics/fluorescents.html.

10. Xiaofei Fan et al., “Abnormal Transient Pupillary Light Reflex in Individuals with ,” Journal of Autism and Developmental Disorders 39, no. 11 (November 2009): 1499–1508, doi:10.1007/s10803-009-0767-7.

11. D. M. Fenton and R. Penney, “The Effects of Fluorescent and Incandescent Lighting on the Repetitive Behaviours of Autistic and Intellectually Handicapped Children,” Journal of Intellectual and Developmental Disability 11, no. 3 (January 1, 1985): 137–41, doi:10.3109/13668258508998632.

13. R. S. Colman et al., “The Effects of Fluorescent and Incandescent Illumination upon Repetitive Behaviors in Autistic Children,” Journal of Autism and 6, no. 2 (June 1976): 157–62.

14. Marylyn Painter, “Fluorescent Lights and Hyperactivity in Children: An Experiment,” Intervention in School and Clinic 12, no. 2 (December 1, 1976): 181–84, doi:10.1177/105345127601200205.