Party lights from phones

Photosensitivity warning: flashing light can trigger seizures in people with photosensitive epilepsy, and can make other people feel unwell. Read the safety section below before using any flashing effect, and ask your guests first.

What makes a good phone light show?

These tips are our own practical suggestions rather than claims from the sources:

Darken the room. Phone screens are small, so they show up best with the main lights off or dimmed.
Spread the phones out. Phones propped on shelves, tables and window sills fill a room better than a cluster on one table.
Keep screens on and bright. A screen that dims or locks halfway through a song breaks the effect. The Party Lights app does this for you during a show.
Plug in if you can. A bright screen for a whole evening uses a lot of battery.
Start soft. Slow washes of colour and gentle pulses are easy on the eye and suit most of a party. Save anything faster for a short moment, and only if nobody minds.

Why soft party lights beat strobes for most rooms

The Epilepsy Society explains that flashing lights at 3 to 30 flashes per second are the common rates to trigger seizures in people with photosensitive epilepsy, although this varies from person to person. It says some people are sensitive at frequencies up to 60 flashes per second, sensitivity under 3 is not common, and lights that flash or flicker between 16 and 25 times a second are the most likely to trigger seizures.

It also notes that strobe lights are not covered by UK law, so their flash rate could be one that triggers a seizure for some people. And it says flashing, flickering or patterned effects can make people with or without epilepsy feel disorientated, uncomfortable or unwell.

That is why a slow wash of colour is a safer default for a mixed group than a strobe.

What UK TV guidance says about flashing

UK television has long had rules for flashing images. The Epilepsy Society says Ofcom restricts the flash rate on UK TV programmes to three per second or less, and also limits how much of the screen can flash.

Ofcom still publishes the older ITC guidance note on flashing images as a legacy document. It explains that a sequence of flashes is not permitted when flashes fill more than a quarter of the screen and there are more than three flashes in any one second. It also warns that a transition to or from saturated red is potentially harmful whatever the brightness, and that flashing lasting more than 5 seconds might be a risk even when it follows the guidelines.

Those rules are written for television, not for parties. Still, they are a useful guide: slow, short and not too much bright red is the cautious way to go.

Safety checklist for flashing effects

These are our own suggestions, based on the guidance above:

Ask first. Check whether anyone at the party has epilepsy or is sensitive to flashing light.
Warn people. If you plan to use a flashing effect, say so before it starts, so anyone can look away or step out.
Keep flashing short. Use it for a moment, not a whole song.
Do not hold a flashing phone near anyone’s face.
Stop at once if anyone feels unwell.

Questions people ask

Can phone party lights cause seizures?

Flashing light can trigger seizures in people with photosensitive epilepsy. The Epilepsy Society names 3 to 30 flashes per second as the common trigger range. Avoid fast flashing effects if anyone may be sensitive.

What are the safest lighting effects for a mixed group?

Slow colour washes and gentle glows, without strobing. They avoid fast flashing altogether.

How do you sync phones lights across a room?

Usually one phone acts as the host and the others follow it. In Party Lights every phone checks its clock against the host and works out the colours itself, so they change together. All the phones need to be on the same Wi-Fi or the host's hotspot.

Where Party Lights helps, and where it does not

Party Lights is our Android party lights app that turns every phone in the room into one light show. One phone hosts, and friends tap Join or scan its QR code to join from the app or a web browser on the same Wi-Fi. Each phone keeps in time with the host and works out the colours itself, so the whole room changes together. It works on your own network, and nothing goes through the internet.

Free: Soft Wash, Beat Pulse and Warm Glow, with a tempo you set or tap along to. A one-time lifetime Pro unlock on the host phone adds room effects such as Wave and Chase, Colour Scenes and your own colours, calm effects, Neon Strobe and Mic Reactive, plus messages and countdowns on every phone. Mic Reactive listens on the host phone only and never records or sends sound. There is no subscription.

Flashing warning: some effects flash. Every phone must accept a photosensitivity warning before any lights start, including guests who join in a web browser, and the flashing effects ask again each time. No effect flashes 3 or more times a second. Still tell your guests before you start, and stick to the softer effects if in doubt.

What it is good for: a simple shared light show at home with friends, without buying extra lights.

What it will not do: all phones need to be on the same network, so it will not link phones across different networks. Phone screens are small and will not light a big room like proper stage lighting.

Questions or bugs: Email us.

Sources

Photosensitive epilepsyEpilepsy Society epilepsysociety.org.uk
ITC Guidance Note for Licensees on Flashing Images and Regular Patterns in Television (legacy document)Ofcom ofcom.org.uk