Sleep alteration in the van der Pol-type circadian pacemaker model driven by natural light and intermittent noise

Sleep/wake cycles were once dictated by the solar day, but now humans are subjected to prolonged exposure to artificial light, resulting in altered daily sleep patterns. We investigate a van der Poltype mathematical model for a circadian model, which incorporates a daylight and noise model, to capture the consequences of artificial light, which has become part of our daily lives. The results show that when the cycle is interpreted as a model for the sleep/awake alternation, the duration and sleep offset are influenced by light intensity, daylight duration and noise intensity. Increasing light intensity and duration can lead to a decrease in sleep duration beyond ∼ 30 mins. Thus, the cycle of the circadian oscillations can be influenced by a sudden change in longitude (jet lag) is much more influenced by the daily duration of light than by its intensity. Noise could cause a loss of sleep of more than 10%; in other words, artificial light could cause a decrease of more than 40 min in sleep time, which could cause a malfunction of the human mechanism.