There are zillions of smart bracelets, fitness trackers of all shapes and forms out there, and it’s hard to know what added value they offer besides tracking  your steps, your running sessions and your sleep patterns. The most advanced have an integrated heart rate monitor, and for people who like to charge devices often, some feature  a nice screen, colored or not. For me personally, they cannot do much, because I do not really run during my workouts, I mainly lift weights and until some manufacturers decide to add RFID tags on each weight to connect with fitness apps, they cannot track my sport activity accurately and completely automatically.

What sets the Sona  Connected Bracelet apart from the rest of the crowd, is its unique high-end heart rate monitoring technology, which combines a cutting edge sensor with a wellness protocol, that was inspired by a method invented by the Russian scientific team who sent the first cosmonauts to space.

On top of the regular activity tracking capabilities offered by other fitness bands, the Sona Connected Bracelet provides a unique feature, based on Resonance, a paced breathing meditation method developed over decades of scientific research. Sona offers five unique guided Resonance sessions, co-developed by scientists and Caeden, which aims at improving focus, calming anxiety, and improving overall stress response.

I played briefly with a prototype of the Sona, and  here you can read  my first impressions. Obviously,  I cannot vouch for the overall quality and battery life of the final product. However, I am pretty enthusiastic about this smart and stylish bracelet, and I will update this hands-on  review article when we will get a review unit. You can watch the video demo above to see how it works.

Key Features

  • SoC / Processors: Dialog Semiconductor DA14580 16MHz; 32-bit ARM Cortex-M0; dedicated ST Micro STM32F401; 32 bit Arm Cortex-M4 sensor processor
  • Connectivity: Bluetooth 4.1 LE, 3 meters minimum range
  • Sensors: Dual ST Micro ultra low-power, high performance MEMS digital output 3-axis accelerometers; Patented photoplethysmography (PPG) biometric sensing system
  • Notifications:  4mm vibrating motor for call and text notifications
  • Storage: 16 MB flash memory, 10 days of continuous data
  • Battery: 80 mAh Lithium Polymer battery – up to 4 days of battery life in active use
  • Charger: Included magnetic charging cable – optional nightstand docking system (pre-order only)
  • Carrying pouch: included
  • Software: iOS app compatible with Apple Health Kit

Price and Availability

sona-modelsSince November 17,  2015, Sona is available for pre-order at a discounted price of $129,  in 3 different models –Rose Gold & White Leather, Gunmetal & Black Leather, Gold & Leather Black – on Caeden website. The $129 discounted price is valid until Nov. 30th, 2015 and the expected ship date is between April 1st, 2016 and June 1st, 2016.

Even the $199 price tag is quite good for the high quality materials and stylish design, and at $129, I consider the Sona Connected Bracelet to be a bargain, if you have the patience to wait until next spring to get it. (Assuming it delivers the high performances we are seeing on the paper.)

Product Design and Hardware

Caeden-Sona-smart-bracelet-08Sona is one of the most elegant connected bracelets I have seen to date, that can be worn either with a casual outfit or a cocktail dress, thanks to its interchangeable bands. In the photo gallery, only the two models that are designed for women are displayed. There is a more masculine version that I have seen (Gunmetal & Black Leather), which is not in my pictures. Made of genuine full grain leather, the band comes in two flavors: black and white. There is an interchangeable silicone band that is available for pre-order only. The premium metal chassis that encloses the electronic components comes in three colors:  rose gold, gunmetal, and gold.

On the hardware side, the key differentiator from other fitness trackers is the heart sensor that is claimed to be 10 times more accurate than the competitive offering, and able to track heart rate variability.

In terms of restandard activity tracking sensors,  Caeden offers similar capabilities as Fitbit, the leading brand on the market, and its Charge HR band: 3-axis accelerometers  and an heart rate sensor (Sona’s HR sensor is 10x more accurate). It gets a vibrating motor as well, for notifications. On the paper, the battery life looks similar: “up to five days” for the Fitbit Charger HR vs. “4 days in active use” for the Sona. Battery life is highly dependent on the intensity of usage, so I would say both devices  might deliver similar battery performance.


The $150 ($149.95 on the official website) Fitbit Charge HR is certainly not elegant, and does not provide any stress management and meditation features based on Heart rate Variability data. The Charger HR offers a tiny screen, which may be better for the people who really need to read their basic data on the band rather than look stylish and fully relaxed in any situation, just like James Bond (or Jane Bond). I would certainly pay a little more to benefit from heart rate variability monitoring and to wear an uber-stylish activity tracker.


Software: Resonance, Heart Rate Variability, Active Time

What is Heart Rate Variability (HRV)?

I met with Nora Levinson, CEO & co-founder Caeden, the company behind the Sona, which is also known for its premium headphones.  During  our meeting, she explained that the Sona’s sensor captures much more detail about my cardiovascular and nervous system than just the standard heart rate BPM, and it requires 10x accuracy over regular HR sensors, according to Nora Levinson.

Sona monitors the heart rate variability (HRV), which is the time lapse between two heartbeats, whereas the standard heart rate is the total number of pulsations in a time duration, the standard measurement is done during one minute. The heart rate variation means that humans produce different numbers of pulsations each minute:  when you are walking the heart beats slower than when you are running, which is totally different from heart rate variability .

When you are under a lot of stress, say under attack, your heart rate tends to skyrocket, your heart produces more beats per minute, but your heart rate variability tends to be very low (low HRV score), because the duration between all pulsations tend to be the exact same in that extreme psychological state – in other words there is no or very little variation of the elapsed time between heartbeats. On the contrary, when you are relaxed and rested, your heart rate is normal, between 60 to 100 beats a minute for non-athlete adults, your HRV score will be higher, because the durations between heartbeats tend to be different in that state.

So basically, in addition to the regular heart rate,  the Sona’s sensor also monitors HRV, which is the variability of the durations between all of your heartbeats. In a relaxed or restful state, your heart beats with different duration between beats, and the human mind and body are more able to adapt to various types of situations, such as learning new information, trying a new yoga position or focusing on solving a problem, for example.

Resonance: a paced breathing meditation method based on HRV data to train resilience to stress


Left: Home Screen with Active Time and Resonance goals – Right; Resonance session including a visual breathing pacer and an audio guidance to help reach your goal

Resonance is a known protocol in the scientific community, and it was pioneered by Dr. Evgeny Vaschillo, PhD, who has been at the forefront of Heart Rate Variability (HRV) research since the 1960’s, pioneering the analysis of HRV and developing Resonance breathing techniques for cosmonauts in the Russian space program. Dr. Evgeny Vaschillo, and his colleague Dr. Bronya Vaschillo, MD, an occupational diseases and methodology specialist, are part of the Caeden team working on Sona.

The Sona application provides the Resonance feature that trains your resilience to stress via breathing and meditation sessions, and it uses HRV data to measure how the user’s heart responds in real time. I tried one session with Nora Levison using a Sona device and the iOS application, and it was pretty efficient to make me relax. I need more sessions to have a real impact on my HRV score and be able to proactively manage my average stress level.  According to Caeden cofounder, users get better at this over time, after performing multiple sessions with the Sona application.


Left: Dashboard of your key achievements – Right: Screen displaying your Heart Rate and Heart rate Variability data to monitor your heart health and stress level

You can read more detailed information on the product site.

Active Time


Active Time section, Energy (calorie burned) screen – in the cropped menu at the bottom the menu where you can access Activity, Energy, Heart Rate, Steps, Distance screens.

Similarly to other connected wearables, Sona’s software delivers regular data regarding your daily activity such as heart rate, calories burned, steps and distance. All these functions are grouped under the Active Time umbrella in Sona’s application while the heart rate variability data is used with the breathing and meditation tutorials available under the Resonance  menu. (See screen shots)

Apple Health Kit compatible

For now there is only an iOS application, and it is compatible with Apple Health Kit, so you can take your data wherever you want to. There will be an Android version, eventually, however, there is no official release date for now.

Q&A with Caeden, co-founder & CEO, Nora Levinson

nora-levinson-caedenLet us know a little about your background, what did you do before starting Caeden?

I have a background in product design and mechanical engineering and spent over 4 years overseeing manufacturing in China for several well-known consumer electronics brands. My first job was at Incase Designs, where I was actually hired by David Watkins, who is now my co-founder at Caeden.  Our time in China was invaluable as we learned how to build products at scale.  After working together for almost a decade, David and I co-founded our first business in 2012, a line of cases and accessories called ADOPTED.

How and when did you decide to start Caeden, the company behind the Sona Connected Bracelet?

With the success of our ADOPTED case line at diverse retailers from Barneys to Best Buy, we realized that we had a unique skillset to execute product that resonated well both in the fashion and consumer electronics worlds. We decided to found Caeden because we wanted to bring this skillset to the wearable technology category in order to create a product that was beautiful, used the most advanced technology available, and solved a real need.  Most products in wearable tech focus on physical fitness and weight loss, but we believe that the bigger problem for modern professionals is trying to find balance while still being productive and high-achieving. There have been decades of research into quantifiable methods to reduce stress, and the sensor technology available for consumer products is finally catching up. We partnered with leading scientists and researchers to take advantage of these advances in sensor technology and build the first consumer product focused on using heart rate variability science to help people achieve their health and wellness goals.

Can you tell us more about Caeden’s scientific team who developed the unique Resonance program featured in the application? 

We are working with Evgeny and Bronya Vaschillo, who have been researching Heart Rate Variability and Resonance breathing since the 1960’s. Evgeny worked in the Russian space program with a team of scientists who were analyzing the EKG signals from cosmonauts, as that was the only biometric measure they could transmit from space at the time. They found that they could use Heart Rate Variability to measure cardiovascular and nervous system function, enabling a better understanding of the cosmonauts’ overall health and how they were doing under the extreme stresses of their environment. Evgeny has an engineering background, and he began to discover that the cardiovascular system displays specific resonance characteristics. He used this insight to develop Resonance breathing techniques, which proved over numerous trials to help improve the cosmonauts’ performance and mental focus. He later teamed up with Bronya, who was already an accomplished physician in her own right, to extend the research to help people with anxiety, PTSD, asthma, and a number of other conditions. It’s been a really amazing experience working with Evgeny and Bronya to help build these decades of research into a consumer-friendly product and share it more widely.

Do you hold a patent?

A lot of the sensor technology we are incorporating is patented.  We are in the process of patenting several of the other innovations and analysis methods that we have built into the technology.

How did you come up with the idea to create this Heart Rate Variability-based feature in an activity tracker?

Heart Rate Variability is a great metric for understanding overall health over time.  We felt that this would provide a new way for our users to learn about their own health and understand how different factors impact them in a measurable way day-to-day. Sensor technology is now just improving to the point of being able to measure HRV in a consumer-friendly form factor.  We wanted to take advantage of these advances and build them into something that people could incorporate into their daily lives and hopefully help them find balance in their health and lifestyle.

The Sona is uber-stylish and fashion trends are changing every quarter. Do you have a plan to offer more customization options to your customers in the future? Or even offer your technology via other leading fashion brands, like Fitbit did with Tory Burch?

We are launching with three color combinations: black leather with gold hardware, white leather with rose gold hardware, and black leather with gunmetal hardware. However, the bands are interchangeable, so this will allow for a lot of great customization options in the future. New band designs will all be compatible with the original hardware, so people can change up their look as new options become available over time. We definitely are considering collaborations, but do not have anything official to announce just yet.

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