While virtual reality headsets have been widely available for a few years, research into their safety – particularly for children – is lagging behind.

Manufacturers of VR headsets give us varying age restrictions. Some recommend users be at least 12 years old, others simply say young children shouldn’t use them, and some say kids should use VR devices only under adult supervision.

The age restrictions aren’t based on medical proof of adverse effects on the brain and vision but reflect the manufacturer’s best guess as to whom the product is safest for.

However, a Leeds University study concluded that a 20-minute VR game caused short-term, but noticeable, vision and balance problems for children ages 8 to 12.

“In a VR device, a virtual three-dimensional world is displayed on a 2D screen and that places strain on the human visual system,” said Mark Mon-Williams, professor of cognitive psychology at Leeds University. “In adults, that can lead to headaches and sore eyes. But with children, the long-term consequences are simply unknown.”

Concerns about the safety of VR devices go beyond physiological issues. A report co-authored by the founding director of Stanford University’s Virtual Human Interaction Lab emphasizes that everything in VR is more intense. A player’s brain processes virtual reality experiences similarly to how it processes actual experiences, potentially leading to feelings of fear, anxiety, disorientation, and excitement that are stronger than with an ordinary video game.

As with any other game, it’s important to research a VR experience beforehand to ensure that the game play, content, and subject matter are age-appropriate.

Until more research is published on the subject, experts recommend limiting the time your child spends using a VR headset just as you would any other screen time, as well as supervising your child while he or she uses the device.