also been linked incrementally to a narrowing of retinal blood vessels — a marker for cardiovascular disease.5
The Brain
The second point of access for screen activities is the brain itself. The brain is evolutionarily designed to respond to stimulating visual input — brightness, color, contrast, and movement — called the orienting response. Back in the day when we had to hunt, gather, or fish for our food, this kind of sensory input suggested the presence of prey or predators, and a rapid response to such input increased our odds of survival. In other words, the orienting response helps us assess a threat before we determine whether to fight or flee. When these stimuli are artificially created, however, the brain’s orienting response gets hijacked, creating chemical, electrical, and mechanical shifts that raise arousal levels. When this happens repeatedly, the brain remains on heightened alert.
Screen devices access the brain on a psychological level as well; video games, for example, are purposely designed to exploit psychological needs and thus activate natural reward pathways, releasing feel-good chemicals in the brain. The brain is attracted to interactive screen-time for other psychological reasons, too, including our need for immediate gratification and responsiveness, aspects that gaming, social media, Internet use, and even texting can provide.
The Body
In addition to effects of electronic screens on the eyes and the brain are the effects on your child’s body. With electronic screen interaction, blood flows away from organs like the gut and reproductive organs and toward the limbs and heart. Heart rate and blood pressure increase and stress hormones are released, preparing the body for fight-or-flight. This reaction might not be surprising when one considers how a child playing an action-oriented video game might respond, but in fact research tells us that all forms of screen-time create subtle changes in the cardiovascular system that can cause damage over time.6 In addition, sitting for lengthy periods of time can cause unhealthy bodily changes within as little as thirty minutes, and the majority of screen-time is spent in a sedentary fashion.
The fact that screen-time is associated with metabolic syndrome is telling. Metabolic syndrome is a combination of high blood pressure, midsection weight gain (“spare tire”), abnormal cholesterol levels, and high fasting blood sugar. It’s a serious condition that can lead to diabetes, heart disease, and stroke. Up until recently, it was rarely seen in children; now it’s become common. It’s unclear why it develops in some but not others, but it’s thought to be related to chronic stress and poor sleep. Even more telling is the fact that the link between metabolic syndrome and screen-time holds true regardless of activity level — a finding that suggests that screen-time produces unhealthy physiological changes that are above and beyond changes seen in those with low activity levels.7
The Biofield
The matrix of biological electromagnetic fields present in the human body represents yet another potential interface between electronics and your child, but this will be discussed in more detail in appendix B on EMFs.
All Revved Up: Fight-or-Flight Mechanisms Related to Screen-Time
Thus, through the eyes, brain, and body, use of electronic screen media sends unnatural and overstimulating messages to the nervous system. Via these pathways, numerous mechanisms promote and maintain the fight-or-flight response, leading to the chronic hyperarousal associated with ESS. It doesn’t take much screen-time exposure for some children to get all revved up because so many mechanisms can occur at once and then feed off one another. Each of these mechanisms is capable of self-perpetuating the stress cycle, while simultaneously lowering a child’s resistance to future stress. Figure 2 depicts the array of screen-related factors that can elicit fight-or-flight reactions. Let’s look at each of these factors in turn.
Figure 2. Screen-related factors contributing to hyperarousal or fight-or-flight
Intense Sensory Stimulation
Screen brightness, quick movements, and supersaturated colors all contribute to visual sensory overload.8 Intense stimulation heightens attention and arousal, feeding into fight-or-flight.9 Furthermore, excessive stimulation can overwhelm the sensory system, causing other parts of the brain to shut down in order to compensate. Afterward, the brain experiences a relative sensory deprivation, which can feel uncomfortable and lead to irritability. Some individuals may even suffer light- or screen-associated seizures, tics, and migraines when intense visual stimulation produces electrical excitability, or the overfiring of brain networks.10 In Japan in 1997, over seven hundred people, mainly children, experienced seizures and vomiting after watching a particular Pokémon cartoon episode that utilized flashing colored lights in a scene depicting two characters in battle.11 The vast majority of victims had never had a seizure before. While extreme, this example shows how intimate the relationship is between the eyes and the brain. We should view the visual effects from electronic screen interaction as a spectrum, with seizures, tics, and migraines representing the more severe or tangible manifestations on one end, and everyday “irritation” and general nervous system dysfunction on the other.
Another sensory-related reaction to extended screen-time is the game transfer phenomenon, where users experience visual hallucinations of game-related objects, like an imprint, after prolonged play.12 Lastly, from a development perspective, repeated exposure to intense sensory stimuli leads to an overactive visual system; the child will attempt to pay attention to everything around him or her, making it difficult to focus and causing other sensory integration issues.13
Psychologically Engaging Content or Activity
Though not all screen activities are games, those that are add another layer to the fight-or-flight story. As the need to win or improve is repeatedly reinforced in some way during play (by earning rewards, escaping from threats, being promoted to the next level, and so on), the player becomes more and more hyperaroused. Meanwhile, the feel-good brain chemical dopamine is continually being released, causing the player to want to continue playing — often for longer than planned. The more engaging a game is, the more it increases dopamine-related attention and arousal, which reinforces itself over time and makes it harder to stop playing. Game designers are absolute geniuses at creating the timing and intensity of in-game rewards.14
In terms of content — for both video game and Internet use — violent, competitive, sexual, vivid, interesting, challenging, and bizarre images and situations all increase arousal or fight-or-flight reactions.15 In terms of game type, role-playing games, such as multimember online role-playing games (MMORPGs), are known to be particularly addicting.16 In part, they may be compelling because they play off of adolescent developmental needs, such as identity formation.17 With younger children, the game Minecraft, which consists of building structures, items, and weapons out of various materials in the form of blocks — activities that seem relatively benign on the surface — is frequently described as “mesmerizing” by parents as their children become “obsessed” with it.18
Disruption of the Body Clock
Both natural and artificial light relay information to the brain and impact the body’s biorhythms, including the sleep-wake cycle, a “circadian rhythm,” and hormone cycles, which have daily, monthly, and seasonal variations.19 As mentioned, when the brain is exposed to the unnaturally bright light of electronic screens, the sleep signal hormone melatonin is suppressed, and natural biorhythms are disrupted.20 Additionally, light from screens tends to be rich in blue tones, which is particularly disruptive because blue light mimics daylight. Low melatonin is linked to depression and inflammatory states — such as cancer and autism — as well as alterations in hormone function, including reproductive hormones.21 Aside from melatonin suppression, light-at-night is associated with other hormonal abnormalities, such as low growth hormone.22 These changes in biorhythms and melatonin production result in poor sleep