Sleep Deprivation in Mice: Looking Beyond the Slow Wave Rebound

Area of Science:

• Neuroscience
• Sleep Science
• Computational Biology

Background:

• Sleep is crucial for neural regulation.
• Aperiodic brain signal components (spectral slope, intercept, knee) and entropy measures are emerging markers of neural states.
• Classical band-limited measures like slow wave activity (SWA) are traditional sleep markers.

Purpose of the Study:

• To compare the sensitivity of broadband spectral metrics against SWA in tracking sleep deprivation effects.
• To investigate sleep homeostasis across different sleep stages using these metrics.
• To evaluate the utility of spectral parameters in mouse models.

Main Methods:

• A 9-day mouse sleep deprivation paradigm (baseline, restriction, recovery) was used.
• Spectral parameters (slope, intercept, knee) were computed using the FOOOF algorithm.
• Broadband spectral metrics were compared with band-limited SWA (0.75-4.5 Hz).

Main Results:

• SWA only distinguished baseline from rebound sleep during NREM sleep.
• Spectral slope and intercept detected sleep deprivation changes in both REM and NREM sleep, indicating broader homeostatic regulation.
• Normalised spectral entropy showed sensitivity to sample size and did not differentiate sleep states.

Conclusions:

• Broadband spectral parameters, particularly slope and intercept, are sensitive to sleep deprivation across sleep stages.
• These fractal measures reflect sleep homeostasis more broadly than SWA, challenging the notion that it's strictly low-frequency bound.
• Broadband spectral analysis offers a valuable complement or alternative to traditional band-limited metrics for sleep-wake dynamics.