virtual reality sickness (VR motion sickness)

What is virtual reality sickness (VR motion sickness)?

Virtual reality sickness (VR motion sickness) is the physical discomfort that occurs when an end user's brain receives conflicting signals about self-movement in a digital environment. VR and augmented reality (AR) are technologies that rely on altering human visual perception -- seeing, hearing and experiencing virtual and augmented environments. VR can provide users with thrilling new experiences that can seem to remove the user from their own physical reality. That experience can be disorienting and uncomfortable for some people, which results in VR sickness.

With VR, there is commonly some form of VR headset that the user must wear. The headset in year's past was particularly bulky. However, newer devices, including Meta's Quest series and Sony's Playstation VR, have increasingly focused on user comfort and optimized to deliver less bulky hardware for VR games and VR experiences. Putting on the headset virtually transports the user into the virtual environment.

The sensation of seeing a virtual reality through the headset can be frenzied in some cases, with a whirlwind of sights and sounds that are different than the real physical world the user was in before they donned the VR headset, no matter how comfortable that headset might be.

It is not uncommon for humans to potentially become disoriented when entering a new environment. The disorientation that users can experience in VR is not about knowing where to look or what to do in a virtual environment or VR game. It's a physical sensation with tangible symptoms. Traditional motion sickness occurs when there is physical motion, such as being in a moving vehicle, plane or a rollercoaster. Motion sickness is a condition that causes nausea, dizziness and general discomfort. While there is no physical motion in VR -- with a headset-based unit -- the immersive nature of the environment tricks the human brain into thinking there is, which can enable the manifestation of VR motion sickness symptoms.

Beyond the symptoms of regular motion sickness, virtual reality sickness is also often associated with headaches, eyestrain and potential drowsiness. Anywhere from 40% to 70% of VR users experience VR motion sickness after only 15 minutes.

What causes VR motion sickness?

VR sickness is generally caused by a mismatch in signals triggered by the VR environment sent to the brain from the users's eyes and inner ear. The discrepancy in sensory cues is what leads to adverse symptoms, including nausea, dizziness and discomfort, similar to traditional motion sickness experienced during real-world travel.

There have been multiple academic research studies into the underlying causes of VR motion sickness. For example, a study published in the American Journal of Ophthalmology in 2019 examined the correlation between VR headset viewing in children and motion sickness. The research found that the conflict between visual and vestibular cues -- cues that are related to the individual's perception of movement and position -- significantly contribute to the onset of symptoms. One of the most comprehensive studies was published in the International Journal of Human-Computing Interaction in 2020, detailing the role of the brain's mismatch detection in the development of virtual reality sickness.

There is also research to support the theory that the following factors can cause VR motion sickness:

• Hardware. These factors can include the display mode and potential visual delay latency. There are also indications that the narrow field of view provided by many VR headsets can lead to feelings of claustrophobia and disorientation.
• Content. These factors include fast-moving graphics and situations. Disorienting or confusing content can heighten the risk of motion sickness. Examples include sudden changes in altitude or speed or unexpected collisions with virtual objects.
• Human. These factors are specific issues related to individual physiology that may make one person more susceptible to VR motion sickness than another. There are also indications that using VR headsets for prolonged periods of time can lead to eye strain, headaches and fatigue, which increases the likelihood of motion sickness.

Who is susceptible to VR motion sickness?

VR motion sickness can potentially impact anyone that puts a VR headset over their eyes and ears. The potential risk exists for individuals of any age or gender. That said, there are some groups that are likely more susceptible than others to fall victim to the disorientation and nausea of VR motion sickness, including the following:

• Children and young adolescents. There is particular risk for children under the age of 13 to VR motion sickness as individuals in that age group are still maturing and developing their vestibular systems.
• Women. There are some some studies that suggest that women might potentially be more susceptible to getting sick from VR usage than men, though the research is far from being conclusive.
• People that normally get motion sickness. Individuals of any age or gender that routinely succumb to motion sickness through physical means, including travel-related sickness, such as sea sickness, are likely to be more susceptible to VR motion sickness. This group could also include individuals that have inner ear problems or are prone to migraine headaches.

How to minimize VR motion sickness

VR motion sickness can be a real impediment to the adoption of VR technologies. However, there are ways for both developers and end users to minimize VR motion sickness, including the following:

• Adjusting default frame rate. The first fix software developers can make to avoid giving users VR motion sickness is to adjust the frame per second (FPS) rate to reduce lag time. VR engineers recommend that, instead of focusing attention on using more processing power to create a sharper picture, developers should focus on increasing the speed at which each frame refreshes to at least 90 FPS. This speed helps reduce delay or shaking in the images as they pass across the screen.
• Improved hardware performance. Newer hardware with improved performance can potentially help, especially when the hardware integrates capabilities that reduce latency. Sensory conflict can be aggravated by latency. If a VR participant looks to the right while wearing a VR helmet, for example, the screen shifts left to ensure the viewer's digital environment matches their physical actions. While this shift appears to be occurring in real time, it occurs in near-real time. While the movement across the screen may seem immediate to the viewer, the lag time still creates a mismatch between what the person's eyes tell them and what their body's tissue sensors are experiencing. Other proposed hardware fixes include using headsets that are placed further from the user's face and using mixed reality instead of VR to provide the viewer with a fixed horizon or visual reference point.
• Testing. Perhaps the best way to avoid VR motion sickness is to test each shot while creating it and expose someone with high sensitivity to frame rates and see how they react. This approach informs developers if their shots are smooth and clean enough to leave users unaffected.

How VR users can avoid getting motion sickness

Minimizing the likelihood of VR motion sickness is also something that individual users can take responsible actions to help limit. Effective methods include the following:

• Start small and take breaks. VR has the potential to be disorienting at first for a new user. Users should start with shorter sessions of five to 10 minutes and gradually increase the duration as they become more comfortable. Whenever they do feel any early onset symptoms of motion sickness, they should take a break immediately.
• Adjust the VR settings. While developers can set a default level for a game or virtual environment, so too can individual users. If a user is having issues, they should lower the graphics quality and adjust the settings to decrease the speed and acceleration of movements in the VR environment.
• Drink water and don't eat a big meal. Staying hydrated is good common sense that is also important when using VR. Users should avoid having a big meal, as well as greasy or spicy foods, before putting on the VR headset.
• Sit instead of standing. There is less risk of motion sickness when users are sitting, rather than standing. If possible, sit in a comfortable, stable chair or seat that can rotate slightly, and make sure it's securely anchored to the floor.
• Use a VR anti-motion sickness device. Dedicated anti-motion sickness devices come in the form of a wristband or bracelet and can provide relief.
• Medication. Common medicines used to treat motion sickness can potentially help treat VR motion sickness as well. The most common medicine is dimenhydrinate, which is sold in the U.S. under the brand name Dramamine.