Review: Pegasi Smart Sleep Glasses II

Pegasi’s 2nd generation of light therapy glasses are smaller, sleeker and easier to use.
Pegasi Smart Glasses II Review


I first heard about Chinese health-tech firm Pegasi via the inaugural Sleep Technology showcase at CES 2017, the world’s largest gadget-showcase of consumer electronics.

The company had just launched their first generation of smart sleep glasses, a simple, easy to use light-therapy product designed to help users sleep better at night, increase energy throughout the day and combat issues caused by disrupted sleep schedules such as shift working and jet lag.

After success with the first generation product, Pegasi are back with Smart Sleep Glasses II. Launched via a successful Kickstarter campaign in the summer of 2018, the new glasses have better ergonomics, battery life and more tweaks that we’ll talk about later.

Compare Pegasi Sleep Glasses Version 1 and 2

But before we talk about the product itself, let’s find out what these smart glasses could do for your sleep?

How can a pair of glasses help you sleep better?

The technology behind Pegasi is derived from 10 years of research conducted by Johns Hopkins University School of Medicine where scientists discovered a new type of light-sensitive cell in our eyes.

These cells had nothing to do with vision but instead they absorbed light as a means to synchronise our internal body clocks.

Because we’ve evolved over millions of years to sleep and wake with the natural cycle of day and night, any disruption to the light/dark cycle can cause not just sleep problems, but also impact our daytime energy levels, moods, concentration, and productivity as a whole.

Certain wavelengths (colours) of light have different effects on us at different times of the days. Blue light or green light in the morning helps to stimulate both the production of cortisol (you can think of this as a ‘wake up’ hormone), but also these wavelengths also block the production of melatonin – the hormone we produce during the night to facilitate restful sleep.

Hence, by controlling the amount of light we’re exposed to at certain times of the day, we can push the ‘reset’ button on our internal clock, helping our circadian rhythms revert back to a ‘natural’ timing whereby you’ll feel suitably energized in the day, and sleepy at night.

Light therapy glasses vs light boxes and lamps

Light therapy is a common treatment for seasonal affective disorder (S.A.D.), a mood disorder that occurs in the winter months when the levels of sunlight are much lower.

But the standard treatment for S.A.D., as well as other circadian rhythm sleep disorders, is by using a light box – an extremely bright standalone full spectrum light which you sit in front of.

Light therapy - light box vs smart glasses
Light box therapy vs wearing Pegasi Smart Glasses II

Whilst definitely not a replacement for clinical bright  light therapy, Pegasi’s smart glasses are designed to give you some of the benefits of using a light box, but you’re able to walk around and do all your normal activities (except perhaps taking a shower…), making the breakfast, checking your emails, without having to interrupt your daily activities.

Why green light instead of blue?

Pegasi Smart Glasses II emit light wavelengths in the green spectrum. Initially I was puzzled why the LEDs weren’t blue or white as this is regarded as the most effective hue to influence melatonin production. So I contacted Renny at Pegasi who directed me to a 2010 study from the Journal of Science and Translational Medicine

Pegasi Smart Glasses II Green Light
Pegasi Smart Glasses II with green wavelength LEDs


The study found that  “while blue-light is usually the most effective way to stimulate the non-visual responses – especially under bright light conditions- stimulation with green light was also capable of eliciting the non-visual responses under certain circumstances.”

Essentially, the research showed that green light activated both the visual receptors (rods and cones) and the non-visual receptors in the eyes. And during tests, for short durations of light exposure, and for light sources of low radiance (brightness), green (555-nm) light was equally effective as blue (460-nm) light at suppressing melatonin.

The study concluded by saying that “light therapy for sleep disorders and other indications might be optimized by stimulating both photoreceptor systems.”

First impressions of the Pegasi Smart Glasses II

Unboxing the Pegasi Smart Glasses, I was pleasantly surprised by the overall quality of the product. Although extremely lightweight and comfortable, the glasses feel solid and of a premium build quality.

The glasses come in either black and white and unlike the first generation, they feature a collapsible frame that’s hinged, so they can fold up when not in use.

Pegasi Smart Glasses II Collapsible
Version 2 of the Pegasi Smart Glasses feature a collapsible frame


Although there’s only one size, there’s a certain amount of flexibility in the frame so that if you wear glasses Pegasi can comfortably sit on top of them.

The design is pleasantly minimal. At a distance, they come across as a pair of large sunglasses (minus the eyeframes of course) and they don’t feel bulky or unwieldy.

The LED’s are hidden in the frame and sit just below your eyebrows, slightly angled downwards to point the light towards your eyes. The nose pad is made of a flexible plastic, which can bend and adjust to fit the width and height of any nose/face.

Regarding buttons and connectivity, there’s just a single on/off switch on the right earpiece and underneath this, a cleverly hidden flap for the micro-USB charging cable. There are also 3 LED indicators which show you the charging status.

A nice touch would have been a carry case, charger or stand for the glasses, but understandably this would have added extra cost.  Plus as the Smart Sleep Glasses II are collapsible, you’re able to use any standard glasses case if you need to travel with them.

In use

Whilst Pegasi describe their product as ‘smart eyewear’, in truth, the glasses are extremely simple to use. There is an app, but you don’t have to use it (more about that later). The basic premise is really simple.

Just put on the glasses first thing in the morning – Pegasi recommends between 7am and 9am – switch on, and the smart glasses will run for 30 minutes and then switch themselves off.

Sleep experts recommend if possible waking with the sun or very bright lights, so starting your day with a 30 minute session with Pegasi is a great way to regulate your sleep patterns.

This was how I used the glasses. They’re now a permanent fixture on my bedside table. Whilst I’ve stopped wearing them everyday, on the occasions where I feel my sleep has been less than optimal, the first thing I do on waking is to put the glasses on, even if I’m lying in bed for a few minutes.

Then, it’s just a case of going about your normal morning routine, albeit with a greenish hue. Even though the light is shining directly in your eyes, the ergonomic design means that as long as you don’t purposefully look upwards into the light, the glow of the LEDs never becomes dazzling or distracting.

Pegasi says the glasses are suitable for pretty much all situations, except driving, and other situations where you need unblocked vision. Also, the glasses are not recommended for children under the age of 13.

The company says if used this way, you should start to notice changes in your sleep quality/energy levels within 7 days.

As well as wearing them first thing in the morning, the glasses can also be used during the daytime as a quick boost of ‘visual caffeine’ if you’re energy levels are low.

Pegasi Smart Glasses II USB socket
Side view of Pegasi Smart Glasses II showing USB charging port

I found the battery life to be excellent. A full charge only takes 70 minutes, and Pegasi say the it will maintain a standby charge for up to 90 days. As the glasses are designed for just 30 minutes use per day, I found a single charge lasted well over 2 weeks.

Did they work for me?

As for my experiences, it’s hard to be objective, but since wearing the smart glasses every morning I have noticed one significant change in my sleep/energy levels.

Usually, in the daytime, especially in the winter months, I’ll feel a noticeable circadian slump in the hours of between 2pm and 5pm. Sometimes the urge is irresistible and if possible I’ll make time to grab a power-nap in the post-lunch period.

But since using the Pegasi glasses I noticed that I’ve been able to power through the afternoons with more focus and energy than normal.

Now, this isn’t a scientific observation, but in terms of tangible effects, it’s certainly something I’ve noticed since using the glasses on a regular basis.

I don’t suffer from any particular sleep disturbances, so I’m not able to say whether or not my sleep has improved, however there is some evidence of clinical efficacy from a trial at the First Hospital of Hebei Medical University where in a test comparing two groups, those who wore Pegasis Smart Sleep Glasses fell asleep 37% quicker than the group who didn’t.

Pegasi app

I actually found it quite refreshing that Pegasi’s smart technology doesn’t actually need to be implemented by software, or complicated setup processes.

In essence, it’s a ‘dumb’ smart product, in that all the technology is built in, you just need to switch it on and make sure it’s charged.

But if you do want to dive deeper into the Pegasi technology, there is an app. It’s called Pegasi Sleep and it’s available both on iOS and Android.

The app allows you to connect your glasses via Bluetooth to monitor battery life, and also set the ‘protocol’. Bluetooth connection was simple and instant, just a single press of the button on the side of the glasses. Bluetooth is only active when you’re connected to the app, so you do

This isn’t explained very well in the instructions, but essentially it controls the brightness of the light and the pre-determined length of time the LEDs stay on.

The default out of the box protocol is a 30 minute duration at standard brightness. You can also choose between ‘Mild’ which is a dimmer light setting that runs for 40 minutes, recommended for people who are sensitive to light, and ‘Strong’, a brighter light which runs for 20 minutes.

Pegasi Smart Glasses II App-min
Pegasi Smart Glasses II App protocol settings

To be honest, I found it quite hard to tell the differences between the difference light settings, even when I tested them in a completely dark room – perhaps I’m not that particularly sensitive to light – so I stuck to the default 30 minute setting.

Another feature in the app that’s not well documented is the Pittsburgh Sleep Quality Index questionnaire. This is a standardised self-reported sleep scoring system that relies on you answering a series of questions over a month long period.

I started completing the questionnaire but gave up when I realised this feature is only applicable if you’re using one of the recommended ‘third-party sleep tracking solutions’. Again, it’s not clear what these solutions are.

Overall, the Pegasi app experience as a whole feels a little unpolished and a bit of a let down in comparison with the high quality of the hardware. What I would have liked to have seen are some features that help users with specific sleep timing issues – for instance if you work shifts or you’re trying to beat the effects of jet-lag.

Hopefully in the future, the company will put more resources into making the app more feature-rich and realise the full potential of what the glasses can do.

Our Verdict

Overall we really like the Pegasi Smart Glasses II.  Light therapy is not a new technology, but the science is proven to be beneficial for sleep problems and many other issues.

The new Pegasi Glasses are a simple to use, high quality light therapy product that let’s you go about your daily tasks without having to interrupt your day. Pegasi’s second generation product is smaller, lighter and less unobtrusive than their first offering, with a sleeker, more minimalist design.

The strength of the product is that it’s really simple to use, just put them on first thing in the morning and after 30 minutes they’ll switch off.

The only let down is the rather lacklustre app. We would have liked to have seen more features that help users who want specific advice on using light therapy for jet-lag and shift work instances.

But if you’re looking for a high-quality, low maintenance product to reap the benefits of light therapy, then the Pegasi Smart Sleep Glasses II are definitely worth taking a look at.

Alternatives to Pegasi Smart Sleep Glasses II

Retimer ($149) was the first pair of smart light therapy glasses to hit the consumer market. A collaboration with Flanders University, Retimer has lots of science behind it, using similar green-blue wavelengths to Pegasi, but sports a slightly wackier design.

Luminette ($199) is a French company that makes a pair of blue light equipped smart sleep glasses. Luminette has a study which showed their glasses performed favourably against a 10,000 lux light box.

Ayo ($299) has a similar design to Pegasi, but uses blue light instead of green. The Ayo light therapy glasses feature a handy carrying case which doubles as a wireless charger.

Jeff Mann Author

Jeff is a certified sleep geek, and the founder and editor of A passionate sleep advocate, he also runs and has been covering the consumer sleep technology industry since 2012.

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