Effects of environmental control before sleeping on autonomic nervous activity

What is it about?

Sleep disorders are one of the causes that impair our quality of life, and adjustment of autonomic nervous activity can improve the sleep quality. The authors examined the effects on the sleep quality with adjustment of autonomic nervous activity by individually optimizing complex environment before sleep. Sixteen subjects underwent an environment optimization experiment during the day and subsequent sleep experiment (9 days/individual) and the ratio of low-frequency to high-frequency (LF/HF) components of heart rate variability was measured during the experiment. The LF/HF decreased under optimal conditions by 19% compared to the control conditions. Next, the effects of optimal conditions before sleep on the sleep quality were evaluated. Based on the index for the sleep quality (light sleep index), effect of the optimal environment conditions before sleep was not clearly observed for all subjects. Clustering analysis was evaluated to analyze the cause deeply. As a result, for the group of experiment subjects who did not feel nervous about the experiment, the light sleep index was decreased under optimal conditions by 29% compared to the control conditions. It was found that the effect on such stimuli could disappear in the subjects who were nervous about the experiment.

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Photo by bruce mars on Unsplash

Photo by bruce mars on Unsplash

Why is it important?

In this paper, our proprietary method for optimizing the multiple environment factors such as air, lighting, aroma and music for each individual in a short period was developed, and it was confirmed that LF/HF decreased by 19% with application of this method. While the effects of controlling the environment during sleep on the quality of sleep have been suggested in the past, no study elucidated the effects of controlling the environment before sleep on the quality of sleep. In this study, the effects on the quality of sleep by adjusting autonomic nervous activity through a control of the environment before sleep were evaluated. Based on the index for the light sleep index, effect of the optimal environment conditions before sleep was not clearly observed for all sixteen subjects. Clustering analysis was evaluated to analyze the cause deeply. As a result, for the group of experiment subjects who did not feel nervous about the experiment, the light sleep index was decreased under optimal conditions by 29% compared to the control conditions. From the result, greater effects were obtained in the group of subjects who seemed to be relaxed during the experiments. It indicates that the stimuli by the optimized environment condition is sufficiently effective in a relaxing daily life.

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