The Best Actigraphy Device to Replace the Philips Actiwatch Spectrum in 2025

1. Introduction

The Philips Actiwatch Spectrum has long been regarded as one of the most trusted tools for researchers and clinicians conducting sleep and circadian rhythm studies. Its combination of light sensing and activity tracking made it a go-to device in both clinical and academic settings. However, with the Actiwatch Spectrum now discontinued, many research teams are left wondering: What’s the best replacement option that meets the same high standards—or even improves upon them?

After a thorough evaluation of available actigraphy devices in 2025, one clear successor stands out: the Fibion Krono. Not only does it match the core functionalities that made the Actiwatch popular, but it also offers several significant upgrades. From superior light sensing and advanced physiological monitoring to researcher-friendly software and participant-focused reporting, the Fibion Krono has emerged as the top research-grade replacement for the Actiwatch Spectrum.

In this article, we’ll break down exactly why the Fibion Krono is the best choice, detailing the features and improvements that make it the natural successor for serious sleep and circadian researchers.

2. Why Fibion Krono is the Best Replacement for Actiwatch Spectrum

2.1 Superior Light Sensing: Multi-Spectral + Flicker Reduction

One of the key features that made the Philips Actiwatch Spectrum valuable was its ability to measure light exposure, particularly RGB light levels. However, the Fibion Krono significantly improves upon this by offering multi-spectral light sensing, capturing not only red, green, and blue light but also infrared and photopic light channels. This provides a more detailed and accurate understanding of the participant’s light environment—critical for circadian rhythm research.

In addition, Krono includes a feature that the Actiwatch lacked: 50/60 Hz flicker reduction. This technology ensures that light measurements remain stable and reliable, even under artificial lighting conditions like LED or fluorescent lights, which can introduce flicker and distort light exposure data. For researchers aiming to assess the impact of both natural and artificial light sources, Krono’s light sensing capabilities are a clear advancement.

2.2 High-Precision Activity Tracking: Triaxial Accelerometer

While the Actiwatch Spectrum relied on a uniaxial accelerometer, the Fibion Krono is equipped with a triaxial accelerometer offering ±2 g range and 0.001 g sensitivity. This allows for much more precise movement detection, capturing motion across three axes instead of one.

For sleep-wake cycle analysis, rest-activity rhythm studies, and physical activity tracking, this level of detail translates to more accurate, granular data. Researchers can confidently interpret participant movement patterns without the limitations of older accelerometry technology.

2.3 Skin-Contact Temperature Sensor: Adds Physiological Depth

The Philips Actiwatch Spectrum did not offer skin temperature monitoring, leaving researchers without access to an important physiological marker of circadian phase. Fibion Krono addresses this gap directly.

It includes a large, skin-contact temperature sensor with ±0.1°C accuracy, ensuring the device records true wrist skin temperature rather than ambient temperature. This additional parameter gives researchers deeper insights into circadian regulation, thermoregulation, and peripheral temperature rhythms.

Moreover, Krono’s temperature sensor is cleverly used as an off-wrist detection mechanism. When the device is removed, the drop in temperature is immediately detected, allowing researchers to automatically flag periods when the participant was not wearing the device—thus improving the reliability and validity of collected data.

2.4 Event Marker Button for Participant Input

Another feature carried over and improved from the Actiwatch Spectrum is the event marker button. Participants can easily press the button to log key events such as lights out, awakenings, or specific activities. This helps synchronize subjective reports with objective sensor data, adding valuable context to the dataset.

2.5 Scientifically Validated in Clinical and Research Studies

Data reliability is non-negotiable in research environments. The Fibion Krono has been scientifically validated, including in clinical settings and studies comparing its outputs to gold-standard polysomnography (PSG). This gives researchers confidence in the accuracy and robustness of the device for sleep and circadian investigations.

3. Advanced Software and Reporting Features: Beyond What Actiwatch Offered

One area where the Fibion Krono particularly excels over the Actiwatch Spectrum is its advanced software ecosystem, designed specifically for researchers’ and participants’ needs.

3.1 Comprehensive Sleep & Circadian Rhythm Analysis Software

The Krono comes with powerful, built-in software capable of performing detailed analyses of sleep patterns, circadian metrics, activity rhythms, light exposure, and skin temperature data. The software automatically generates reports tailored for scientific research, helping streamline workflows and save valuable analysis time.

Researchers can also access raw data exports, offering full flexibility for custom analysis and integration with other datasets.

3.2 Participant-Friendly Feedback Reports

Beyond researcher-focused reporting, the Fibion Krono’s software includes clear, easy-to-understand feedback reports designed for participants. These summaries provide participants with insights into their sleep and activity patterns in a simple, visual format—encouraging higher compliance and engagement throughout the study period. This is an area where Actiwatch users previously had limited options, and Krono delivers a noticeable upgrade.

4. Conclusion: Why Fibion Krono is the Natural Successor to Actiwatch Spectrum

With the discontinuation of the Philips Actiwatch Spectrum, many researchers face the challenge of finding a reliable, validated replacement that not only matches the Actiwatch’s capabilities but also offers meaningful improvements. After careful consideration, it’s clear that the Fibion Krono is the best choice available in 2025.

By providing multi-spectral light sensing with flicker reduction, a high-accuracy triaxial accelerometer, and an advanced skin-contact temperature sensor that also detects off-wrist periods, Krono delivers a level of precision that exceeds what the Actiwatch offered. Additionally, it retains crucial features like the event marker button, ensuring researchers can align subjective reports with objective data seamlessly.

What sets Fibion Krono apart even further is its powerful analysis software, which not only produces comprehensive, researcher-focused circadian and sleep reports but also generates participant-friendly feedback summaries—a clear upgrade over the limited output options of the Actiwatch Spectrum.

For researchers seeking a validated, research-grade, all-in-one solution to replace the Actiwatch Spectrum, the Fibion Krono stands out as the natural successor, offering unmatched data quality, usability, and flexibility for advanced sleep and circadian research.

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