Virtual reality offers unique experiences for humans and can also strain and challenge many of our bodily and psychological systems. Taking the recommended 10- to 15-minute breaks every 30 minutes – or sooner if you feel unwell – and following other guidelines are essential to enjoying VR in a manner that respects its power and safeguards both yourself and those around you.
Using a VR headset can cause eyestrain just like staring at any glowing screen. Myopia, or nearsightedness, 
Another visual issue that comes up with VR is called the vergence-accommodation conflict. Vergence is when your two eyes converge or diverge to see an object; converging for closer things and diverging for those far away. Then your lenses practice accommodation or focusing on the object. Stereoscopic VR headsets present two images at slightly different angles to your right and left eyes, which creates a 3D effect. Stereoscope viewers were first invented in the mid-1800s. With a VR headset on, your eyes are interacting with a nearby screen that is telling them some things are farer away -- this is the confusing vergence-accommodation conflict.
VR tells your brain you are in a setting with sights, sounds, beings and objects different from where you were moments ago and from what many of your body’s senses are still receiving. Disorientation, dizziness, nausea or a combination sometimes called “sim sickness” or “cybersickness” are common reactions to these conflicting sources of information. Along with being negative experiences on their own, they can lead to falls or other unintended encounters with the natural environment, such as striking another person or an object like a ceiling fan. Oculus Rift’s safety video illustrates this below:
Games that involve flying or high speeds can worsen the effects. Some innovations in VR, including MONKEYmedia’s “BodyNav” system, seek to reduce bodily confusion and disorientation by letting players control VR movements with their head and torso, rather than with hand controls.
People with a variety of health risks or issues, including those who are “pregnant, elderly or have pre-existing conditions that may affect [their] virtual reality experience such as vision abnormalities, psychiatric disorders, heart conditions or other serious medical conditions,” are encouraged to see a doctor before using the tech in most VR product warnings. The use of implanted medical devices or a history of seizures are also usually included in the advisory statements.
"[D]on't think of VR as a 'media experience,' because the brain sees it as similar to an actual experience," Jeremy Bailenson, director of Stanford's Virtual Human Interaction Lab, told CNN. He’s been studying how VR effects human perspectives on life along with traits such as empathy and social responsibility.
Bailenson and his team have found that people respond to using VR in a stronger fashion than they do to video or role-playing experiences. For example, the Stanford researchers discovered VR can boost adults’ feelings of connection to the natural environment; a VR tree cutting experience resulted in participants consuming notably less paper than those who learned about tree cutting through print and video sources. They have also seen that children are particularly susceptible to confusing VR immersions and memories with reality and that teens react negatively to social exclusion in virtual worlds. Most VR headset instructions explain they are for ages 12 or 13 and up or are not for children’s use at all.
Google's Daydream View’s health and safety page also states:
"If the content is frightening, violent or anxiety-provoking, it can cause your body to react physically, including increasing your heart rate and blood pressure. It can also, in some individuals, cause psychological reactions, including anxiety, fear or even Post Traumatic Stress Disorder."
"If it's an activity that you're ethically not comfortable with in real life, don't do it [in VR],” Bailenson said. He thinks children can probably safely use VR in small doses if guided and monitored by adults. His own 6-year-old daughter has used it in four sessions of five minutes each.
More than a million VR headsets were sold in the third quarter of 2017 alone. VR’s long-term effects on the human body and psyche and on youth, in particular, are yet to be determined. Everyone using VR should take all recommended precautions and breaks and pay attention to how they feel -- this article is not intended to serve as medical advice.
Marientina Gotsis, associate professor at the University of Southern California Interactive Media and Games Division, said "someone needs to watch over you when you are using VR. That's mandatory."
Jack McNee, who holds the Guinness World Record for the longest use of VR, stayed in the Tilt Brush game for over 36 hours in 2017. He did have 10-minute breaks every hour and could bank the breaks into longer segments. After finishing this marathon, he said, “I feel nothing from like my neck down … It’s all in my head.” More below:
