2022.07.23

Effect of Hibiscus syriacus Linnaeus extract and its active constituent, saponarin, in animal models of stress-induced sleep disturbances and pentobarbital-induced sleep. 2022

2.12. Piezoelectric monitoring

To reconfirm the sleep improvement effect of HSF extract after EEG recording, a noninvasive automatic sleep/awakening scoring system (PiezoSleep, Signal Solutions, LLC) was applied to the mice. Each animal was placed in a customized clear acrylic open-floor cage, and sleep rates were recorded by the piezoelectric floor pad under the cage. The recording room maintained fixed light/dark cycles, temperature, and humidity, and the experimenter had restricted access. After 1 week of restraint stress, the mice were immediately placed in an acrylic cage with a piezoelectric sensor, and their activity was recorded for 24 h starting at approximately 6 p.m. The records of light/dark sleep rates, hourly sleep rates, sleep durations, etc. were analyzed using the SleepStats2p18 software (Signal Solutions, LLC).

Noninvasive, Automated Measurement of Sleep, Wake and Breathing in Rodents

• Q: How does the PiezoSleep system distinguish between inactivity (quiet wake) vs. sleep?
• A: The piezo sleep signal is characterized by a steady 2.5-3.5 Hz breathing feature, while quiet wake has additional small movements causing irregularities in the signal. These differences are included in the automated sleep/wake scoring algorithm. By visual observation, the PiezoSleep software routinely correctly identifies quiet wake as wake, such as when the mouse is sitting quietly, sniffing, grooming, etc
• Q: Is external cage vibration an issue for this system? Do the cages need to be put on an "anti-vibration" table to avoid interferences?
• A: Normal static racks and cabinets are typically used to conduct sleep experiments, however for optimal results, the piezo system should be set up in a room that is as quiet as possible. In any new environment, a twenty-four-hour run with empty cages should be performed to determine whether any air movements or vibrations from vents, fans, machinery, other equipment, etc. are present that could compromise results. Any external signal could potentially mask or interfere with the biological signals from mouse activity. Facility HVAC systems often have blowers that come on at certain times of the day, and it is important to optimize rack and cage placement away from air vents to minimize air blowing into the cage and across the sensor. If strong air currents or vibrations are detected in an empty cage run, sensors can be shielded by re-positioning the rack, or physically blocking the air flow in the vicinity of the cages. In any experiment using sensitive equipment, the quieter the room, the better the results. Good practices for any sleep experiment include reducing disturbances from personnel doing routine checks, rescheduling other experiments in the same room to avoid waking mice during their normal sleep period (light period), making sure the timers for lights on/off are working properly, and other common sense precautions to minimize disruptions.

Diering Lab   Graham H. Diering

source: https://dieringlab.web.unc.edu/author/allf/