Does light therapy work? The science of stroboscopic stimulation

0:00Katie Edwards:Not many people know that with closed eyes, stroboscopic light can create these vivid visual hallucinations.

0:06David Schwartzman:You look like a fly. I do not. I look like Jenny Farnston. Get lost. Look at that. I actually started to see mountains and stuff as if I was walking through mountains. Oh, interesting. What on earth is going on with that, David? Hello and welcome to Strange Health from the Conversation, the show where we explore the weird and wonderful stuff that your body gets up to. I'm Katie Edwards and I'm health and medicine editor at The Conversation in the UK. We're an independent source of news and analysis powered by academics and journalists working to make evidence accessible. And I'm Bam Gort and I'm a GP and lecturer in health and life sciences at the University of Bristol.

0:52David Schwartzman:All right then Dan, So today we're going to be looking at light, the powers of light. And this episode has been inspired by, you know, that picture of Jennifer Aniston. She's laying on a bed and she's got them. Oh, yeah, I know. I know exactly which one you talk about. She's absolutely raves about stroboscopic lights. Yeah. Well, I mean, anything that's good enough for Jennifer Aniston is good enough for me. Look at that. Yeah. So this is a product that Jennifer Aniston has been using and it's called the Luminate Nova. And basically it kind of pulses that into your eyes and it's supposed to calm you down.

1:32David Schwartzman:I think the idea is that it calms the noise down in your brain. So if you struggle, you know, with a lot of thoughts and things like that, this helps you to focus. So what's it like when you put it on then, Katie? It's really unusual. So I'm just going to pop it on for you now because I do look quite good in it. so there we go as you can see you look like a fly

1:59David Schwartzman:right well anyway thanks i've gone from jenny franiston to jeff goldblum in one fell swoop but thank you very much um so i put it on and i wasn't expecting much at all because to be honest with you i thought it might be a bit of a gimmick um so i tried it first of all I gave it to my older brother he's really struggles to sleep a lot and he was interested to try it and he's very very dry person and I thought he was going to say it was rubbish so anyway we sat there and he took the mask off when it had finished and I said what did you think of that and he went absolutely brilliant amazing and so this is coming from like fairly big cynic you'd say yeah and yeah proper miserable so I thought oh I'll have a go at it when I put it on I thought oh this is just like shutting your eyes you know like you get them lights and stuff when you shut your eyes I thought oh it's just like that but then after a while I got into this this makes me sound balmy which probably is true but I was walking through this like mountain region and then I started feeling warmer and there was sun coming from that like that angle and I thought oh of course it's getting warm isn't it but it wasn't obviously it was just my mind yeah it was doing it I must be just like very open to suggestion or something because I really did feel like I'd been transported to somewhere else I thought it was quite good I don't know if it like I sleep like a log I've got no issue sleeping yeah me too it made no difference no but it did definitely like I do have I've got a very active brain a lot goes on up there but it did actually calm my head down for a bit.

3:43David Schwartzman:So what is all that about then, Dan? Is there actual science behind this? So stroboscopic light is a light source which basically mitts light in a pulse frequency rather than continuously. Do you remember those optical illusions that Victorian children have, you know, before the advent of Peppa Pig and such things? Dan, Dan, why would I remember optical illusions that the Victorians have? Think back, you must have done. Sorry, the cheek, the absolute cheek. I could be making a gesture at you, but I'm doing it under the desk. They used to have these sort of mechanical contraptions. They were called zootropes.

4:16David Schwartzman:And they had slits on them, which sort of had a canister which spun. And there would be a picture on the inside of it. And essentially what happened is it made the picture look like it was moving rather than stationary. Same sort of effect, really. And stroboscopic lights, you can tend to think as well of these days as sort of like the lights that you see on like a Daft Punk concert or something like that. something which makes it look like you're moving much more slowly than you're actually doing. Well, to find out more about stroboscopic light stimulation and how it all works, I called up an expert who's been running some experiments on this, like huge experiments, in our Ask the Expert section.

4:56David Schwartzman:So David Schwartzman, you're a research fellow at the Sussex Centre for Consciousness Science at the University of Sussex, where you research effects of stroboscopic light. Welcome to Strange Health. Thank you very much for having me. Well, it's great to have you here because I've got myself one of these things. Oh, I'll just put it the right way around. So I got sent it and I thought, like, you know, what are the chances of it actually doing anything? and I actually started to see mountains and stuff as if I was walking through mountains oh interesting and then I saw like some light I don't know if I might be this might be giving stuff away if I uh you might find out all sorts about my psyche through this but then I felt some light and I thought oh it's getting warmer but of course it wasn't getting warmer at all that was just me imagining it because I could see light what on earth is going on with that David

5:56Katie Edwards:well um so what you're experiencing there are called stroboscopic visual hallucinations and so yeah most people are really surprised by that because we all have context we know about stroboscopic light and we've seen it in nightclubs or theaters but not many people know that with closed eyes stroboscopic light can create these vivid visual hallucinations of geometric patterns of dynamic shifts in in color kaleidoscopic imagery um and what you were describing there are what we term complex hallucinations so hallucinations that have some semantic meaning to them so uh places object scenes or in your case uh strolling through some some mountains and this illuminate um nova goggles that you've got is like the first kind of commercial accessible offering that allows people to have these types of experience within the comfort of their own home you've tried it then what do you see i've had complex hallucinations like you described so really vivid uh experience that i would term as being almost more real than than reality but the majority of the time i have these simple geometric patterns uh dynamic swirling vortices um and those types of experience people have different susceptibility to stroboscopic light there's just very basic physiological reasons why that might be so uh the thickness of your eyelids pigmentation of your skin because at the end of the day the light is still passing through your eyelids and hitting the retina to create these visual experiences.

7:43David Schwartzman:What is going on in your brain when this happens then? Because it's kind of like psychedelic, isn't it?

7:48Katie Edwards:It is. It is. And there's a lot of overlap between the types of experience that people report under strobe and psychedelics, as well as a number of other conditions and induction methods. But what's happening is that that stroboscopic light is entraining your brain activity. So in your visual cortex so it's synchronizing the on and the off flash of the light entrains the signal of your brain to that specific frequency and when that frequency happens to be within the brain's natural resting rhythm so between around 8 to 12 hertz these neurons start to oscillate and fire in sync with each other and so that creates patterns of activity that spread throughout the visual cortex and your brain does what your brain is best at, which is interpreting these signals as visual experiences.

8:43David Schwartzman:So how did you get into studying this?

8:46Katie Edwards:So in 2012, I joined the Sussex Centre for Consciousness Science, and we were holding the annual consciousness conference. And so I helped create this public engagement event where we had over 50 little stores and people could come in they could try have demos on different uh different little experiments and uh pieces of art that people brought in which all revealed something about the nature of consciousness um and like a random friend said oh well we have these um two austrian doctors that have developed this strobe light which is actually sitting in the background here this uh lucia number three and it creates this hypnagogic experience so that transition between wakefulness and sleep and so i was like oh well that sounds perfect um and so on the day i didn't have chance to experience it myself they brought like a little tent along and took people in and gave them a brief demo but as i was walking past i saw people and they were like staggering out of the tent going oh my god that was an amazing experience and later I had a go myself and I realized the the potential of this method as a controllable means that we can induce hallucinatory experiences in people and study them as part of a center's remit which is you know understand the biological

10:15David Schwartzman:basis of consciousness connect consciousness with stroboscopic lighting for me so first

10:21Katie Edwards:these types of hallucinations are surprisingly common so people think of them as exotic rare experiences but they actually occur across a wide range of conditions like parkinson's disease they occur in a lot of eye related disorders so age related macular degeneration where people are losing the central vision with age and that leads to a condition called charles-brunay syndrome and they have these types of hallucinations quite similar to the ones that you experience. People with migraines have these types of hallucinations, sleep-related state, and there's a wide range of pharmacological methods of inducing them.

11:06Katie Edwards:So psychedelic drugs have very similar effects. So they're not just a clinical curiosity. They tell us about the nature of conscious experience and the wider range of possible conscious experience. Second, they kind of help us to understand how the brain constructs reality in some sense. So that's the kind of link with consciousness science is, you know, if we can understand how hallucinations occur in the brain, this allows us to understand more about how our vivid, amazing experience of the world also occurs.

11:46David Schwartzman:That's fascinating. So tell me a bit about the history then of stroboscopic lights. When did people start experimenting with just flashing lights in front of their eyes?

11:57Katie Edwards:It's got quite a long history. So the first scientific documentation of these types of hallucinations was by a Czech anatomist called Jan Pekinji in 1819, so over 200 years ago. and he just had a candle on his desk and he would put out his hand and use his fingers as like an aperture and with closed eyes he would move his hand backwards and forwards and he noticed that that elicited these types of of patterns and over the years they were also studied for hallucinations in their own right but also telling us about how vision is constructed in the brain and these these kind of early days um as well as uh for how visual stimulation affects brain activity so it was used quite widely uh but still quite a fringe topic within within science um and then we move forward to like the 1960s uh so good old days with the creation of something called the dream machine so this was by a beat artist called brian gyson and a mathematician called ian somerville they created this device which was very kind of ad hoc put together from things that they had lying around the house so it would be a record player and they'd cut out specific patterns in this cylinder of card and they'd hang a light bulb in the middle of it so you'd have that illumination coming from the inside out start the record player the cylinder of card would spin round and it just happened that that rotational speed was within this uh sweet spot for inducing uh visual hallucinations and this was like widely used throughout the 60s and was quite a big part of the kind of beat movement um in the uk and wider afield and widely influential in the counterculture at the times, influencing people like William Burroughs and the like.

14:08Katie Edwards:So yeah, it was quite a big thing.

14:12David Schwartzman:That's literally like two blokes in a living room looking through a bit of cardboard with some music. Have they not just made a club in the lounge? Yeah.

14:21Katie Edwards:Gyson's vision was that this was going to replace the television. So people, you know, instead of a TV, every house would have one of these and people would sit around it with eyes closed having these hallucinatory uh altered state experiences um so didn't quite turn out that way that was optimistic to be fair i want it it was it was but then in uh 2022 we were involved with kind of like a modern reimagining of this dream machine uh experience that we we ran as part of the Unboxed in the UK, which was a government-funded arts festival. So no longer using this kind of basic technology, we're using proper full-powered stroboscope.

15:08Katie Edwards:And we collaborated with artists and engineers to build this dream machine, which could allow 30 to 40 people to come in and have this immersive experience it was open to the public and it toured the capitals of the uk in 2022 and allowed over 40 000 people to have these types of experience so it's a circular circular couch allowed people to lie down the holes behind each person's head were speakers So we had this, it's called ambisonic sound, which is a 360 soundscape. And the music artist, John Hopkins, created a bespoke track for us. And the music was synchronized to the stroboscopic experience.

15:58Katie Edwards:And it was very curated. So we went through a lot of time and effort to make sure this was a safe and inclusive space that allowed people to have these experiences. and then when they come out they had the opportunity to draw their experiences we just said you know whatever you want to draw about your experience just uh put it down and um yeah so people had overwhelmingly positive response so there was you know immediate increases in

16:28David Schwartzman:in people's well-being i can see obviously your dream machine you know 2022 is quite different from your cardboard cutout box, which was ingenious, no doubt, but, you know, a little bit rudimentary there. So can you show – you said you've got a stroboscope behind you.

16:50Katie Edwards:Yes, yeah, yeah, yeah. Let's have a look. Can we have a look? Yeah, so I can bring it a little bit closer. So, you know, modern stroboscopes just allow you to control all of the parameters that go into the stroboscopic light. So obviously you have the brightness of the light and how quickly it flashes per second. So really the useful range is from about five times a second up to about 40 times a second. That gives the most interesting visual experiences. And that's one of the things that we're doing with my students and my research here. it's kind of like mapping how those parameters relate to specific types of experience.

17:38David Schwartzman:Are there any medical uses for strobostropic lighting, you know, like as a kind of therapy, like what evidence is there for that?

17:46Katie Edwards:We nearly finished a Medical Research Council funded project looking into the therapeutic potential of strobe for depression. So off the back of the dream machine, there was many cases of people reporting general well-being, but also improvement of their depressive symptoms so we had some uh people who had treatment resistant depression they came in and they came out and they were like oh my god i for for the first time in 10 years i feel like the depression has lifted uh i feel fine uh how can i do this where can i do this again and so we were wondering you know well what what possible mechanism could there be there and the biggest motivation was evidence from psychedelic therapy as i said so as well as the psychedelic drugs converging evidence suggests that it's the acute experience during a psychedelic trip which predicts clinical benefit so experiences of or of alterations in how people see their self widening of perception of possibilities all of these things are shown to predict if someone's going to respond to depression and a lot of these same types of experiences can be induced by stroboscopic stimulation so we were just going down this experience centered mechanism that if we can create similar experiences with strobe to psychedelics maybe we don't need the drugs maybe this could be a non-pharmacological easier to access because obviously there's going to be all kinds of legal and practical constraints around giving people with depression psychedelic drugs and so yeah this study that we're running we're just completing now was an initial step looking at the safety how tolerable it was for people with depression and the feasibility of just running this at scale and we have encouraging signs that people feel better after these sessions so the design of the study is that we have people come in once a week for four weeks and they have a half an hour strobe experience so just behind me in the office we have a soundproof booth and outside the booth shining through a window we have a stroboscope set up and they put on the earphones and listen to a track that is tuned or synchronized to the flashing of the light and we look at how they feel before and after they finished the entire study and yeah so so the next trial we're moving on and looking for what we call a signal of efficacy for this type of novel approach to treating depression how safe is this

20:47David Schwartzman:then is there like a time limit are you not supposed to stay in it for you know ages or would it i don't know disturb the balance of your mind if you did it for too long

20:58Katie Edwards:what are the links to it okay yeah yeah sure sure so i mean overall it is extremely safe um so the main medical risk uh as everyone is aware is is a photosensitive epileptic seizure but there's a common misconception in in the public and and me before i got into this field that all people with epilepsy have a photosensitivity so that they are likely to to have a seizure in front of stroboscopic light and actually it's a very small percentage of people with epilepsy have the photosensitive variant so it's only about three to five percent of people with epilepsy can be triggered with a strobe light so you know the risk is non-zero but it certainly is low the main medical sensitivity is epilepsy but there's a lot of conditions where people might be finding bright lights aversive or just uncomfortable so sometimes it can make your eyes flutter a little bit or it can induce a mild headache in certain people.

22:07Katie Edwards:But still, that's really low. So it's like maybe 2 % of that entire sample. And so for those, you know, we need to just make sure people are aware before going into strobe what it's going to entail.

22:22David Schwartzman:Does anybody not see anything?

22:24Katie Edwards:Yeah, surprised. I had the strangest conversation. I talked to them in detail about it because I was fascinated uh so we had a visitor to the dream machine and they were just surprised they were like what uh what was meant to happen and i was like what so so i so you didn't see anything and they had no visual experience whatsoever um and so i like i said i can only put it down to maybe this this lady had just really thick eyelids that didn't allow light to pass through it i just have no other explanation uh because it's you know it's just typically it immediately induces these types of experiences in people within the focus group testing we had all kind of interesting populations just to see you know if it was safe for them to come in so we had people with epilepsy come in and experience the dream machine and they loved it they thought it was amazing uh and we also had visually impaired people come in and so these people all of them are legally blind but they have some preserved vision and they were just crying afterwards because they had these profound visual experiences that maybe they hadn't have ever in their life or maybe it had been 10-15 years and they were like oh my god i saw colors i saw vivid patterns and shapes and we had people with aphantasia so this is the lack of any kind of visual imagery so they just have a blank mind when they imagine anything nothing is there um and they have visual experiences as well and so they're like oh my god this is what it's like to have a an internal visual image in the mind you know so um it can be really powerful you can imagine there could be therapeutical interesting applications with those specific populations um but yeah one thing at a time we need to focus on uh depression and well-being that's where we're going at the moment

24:24David Schwartzman:and what do you think about the the devices that are becoming commercially available now

24:29Katie Edwards:i think that they're all really good so i i've i've got a illuminate nova as well and i've been trying out i think it's it's very very relaxing very very calm relatively compared to something like this they're very mild experiences right so you know like like i'd say illuminate nova would be like on a two or three on a 10 point scale whereas dream machine that was like maybe a six or a seven and something like this one we could go all the way up to 11 if we wanted to you know like so so the the intensity the range of the visuals the types of experiences that we can induce very much depends on the device and the brightness of the light that's uh being shown on

25:12David Schwartzman:on closed eyes wow an 11 yeah imagine have you have you done that oh yeah of course of course

25:19Katie Edwards:yeah when we were developing uh dream machine we went through kind of a year's r &d uh so you know like how to do this at scale and so to start with we had these uh theater strobe lights and we had like a bank of them and we were lying like one meter underneath of them and still to this day It's like a flashbulb memory. I have a vivid... So I was in some kind of geometric space with bright reds and oranges and the whole room was made out of these... It was kind of like Minecraft, like it was a blocky world. And I was just standing in this middle of this massive hall made out of these luminescent blocks.

25:59Katie Edwards:And it was incredible.

26:02David Schwartzman:And what kind of research then do you imagine is going to be done in the future with this kind of technology what are you what are you going to be up to next so you know i think the

26:10Katie Edwards:therapeutic angle um depending on on how successful uh our research is i think that's definitely one way to go um it's been used for a treatment for alzheimer's disease so we're already in phase three clinical trials in america um and so the the logic behind that is they just happen to notice that people with Alzheimer's disease can't produce faster brain oscillations. So anything above like 30 hertz is really diminished in people with Alzheimer's. And leveraging this entrainment property that I talked about of stroboscopic light, they thought, hmm, what would happen if we forced the brain to oscillate at faster speeds?

26:56Katie Edwards:So they picked 40 hertz, and they just sit people in front of that for half an hour a day and certainly in animal models so where we develop a model that shows the same kind of pathology as a clinical condition in animal models half an hour a day stroboscopic light at 40 hertz dramatically reduced amyloid plaque load in these models amyloid plaques are the the proteins which are kind of gumming up how the brain can work so they interfere with neural transmission and you find them all over the brain so it's a really it's quite a difficult thing to treat because it is quite diffuse um so yeah forcing the brain to oscillate at these higher speeds would shake off these plaques almost immediately so that's that's one direction in which uh i think the research is going but you know as i was saying you know just as a general interesting way of studying uh hallucinations and perception and as a model of hallucinations I think that's really interesting you know part of our research here is is mapping the experience of these hallucinations and you know from one condition to another there are similarities but there's also differences and so maybe those differences are telling us something about the underlying pathology and how we could potentially treat that or improve the the symptoms