A thermodynamic model of the REM–NREM sleep cycle

Although many models explain the spontaneous alternation between two distinct sleep states, Rapid Eye Movement (REM) and Non-Rapid Eye Movement (NREM), new empirical evidence has accumulated regarding consistent temperature changes during sleep stage transitions in small animals. The temperature dependence of neuro-excitability and low-frequency ( ≤ 4 Hz) neuronal activity has also been investigated theoretically and experimentally. Based on these phenomena, we constructed a stochastic thermodynamic model of the ultradian sleep rhythm. The model was validated through simulation, demonstrating statistical properties that align with experimental data from rats. This model would provide new insights into the mechanisms behind the REM cycle and can be applied in new therapies for sleep disorders. • A new stochastic thermodynamic model of the REM–NREM sleep cycle. • Integrating empirical temperature fluctuations on sleep stage transitions. • Accountable for the temperature dependent neural firing and neuronal noise. • Validation with rat’s empirical sleep data through simulation. • Potential insights into developing thermal therapies for sleep disorders.