Sleep and circadian rhythm disruptions are common to many conditions and are associated with negative consequences such as cognitive impairment and metabolic dysfunction. Though sleep is highly relevant to many areas of behavioral research, measurements are rarely taken as they require specialised equipment and expertise. Current methods for continuous measurement of activity and sleep in mice are either too blunt, only measuring one feature of activity such as a microswitch equipped running wheel that is not a reliable indicator of sleep, or require invasive surgeries, such as electrophysiology using implanted electrodes. Therefore, Laurence Brown and colleagues created the Continuous Open Mouse Phenotyping of Activity and Sleep Status (COMPASS) system.
COMPASS is a low-cost, non-invasive activity and sleep measurement system that uses passive infrared sensors and an Arduino microprocessor. The system avoids the use of a continuously recording camera that would produce large files, instead opting for simple measures of movement via motion sensing that produce small files that can analysed and shared easily and can be processed in real time. The group has previously validated the system against EEG/EMG data supporting accurate sleep measurements in their 2017 paper. Their most recent paper describes the step-by-step protocol for assembling COMPASS as well as provides support protocols and python scripts for data analysis, best practices for optimum results, troubleshooting, and alternative protocols for different use scenarios. COMPASS is therefore a relatively easy, low-cost way to incorporate sleep measurements into your research.