Regular Late Bedtime Significantly Affects the Skin Physiological Characteristics and Skin Bacterial Microbiome

Abstract

Background: Late bedtime is a common form of unhealthy sleep pattern in adulthood, which influences circadian rhythm, and negatively affects health. However, little is known about the effect of regular late bedtime on skin characteristics, particularly on skin microbiome.

Objective: To investigate the changes and effects of the regular late bedtime on skin physiological parameters and facial bacterial microbiome of 219 cases of Chinese women aged 18-38 years living in Shanghai.

Methods: Based on the Self-Evaluation Questionnaire, bedtime was categorized as 11:00 PM; thus, the volunteers were divided into early bedtime group (S0) and late bedtime group (S1). The physiological parameters of facial skin were measured by non-invasive instrumental methods, and the skin microbiome was analyzed by 16S rRNA high-throughput sequencing.

Results: The skin physiological parameters of the late bedtime group exhibited significant decrease in skin hydration content, skin firmness (F4) and elasticity (R2), while TEWL, sebum and wrinkle significantly increased. The result indicated that late bedtime significantly impaired the integrity of skin barrier, damaged skin structure, and disrupted water-oil balance. Furthermore, the analysis of α-diversity, Sobs, Ace and Chao index were found to significantly decrease (P < 0.05) in the late bedtime group, suggesting that late bedtime reduced both the abundance and the diversity of facial bacterial microbiota. Moreover, the abundance of Pseudomonas increased significantly, while Streptococcus, Stenotrophomonas, Acinetobacter, Haemophilus, Actinomyces and Neisseria decreased significantly. In addition, Spearman correlation analysis revealed strong correlations between the microbiota and the physiological parameters. Notably, the abundance of Pseudomonas significantly positively correlated with skin firmness and elasticity, but significantly negatively correlated with skin hemoglobin content, melanin content and skin hydration.

Conclusion: Bedtime is an important factor in maintaining skin health. Regular late bedtime not only damages the skin barrier and skin structure but also reduces the diversity and composition of facial bacterial microbiome.

Keywords: late bedtime; skin barrier; skin biophysical property; skin microbiota; sleep.

Figure 1

Skin physiological parameters in early bedtime group (S0) and late bedtime group (S1). Significant differences were shown in the figure. (A) Hydration, (B) TEWL, (C) Sebum, (D) Melanin, (E) Hemoglobin, (F) R2, (G) F4 and (H) Wrinkle. *P < 0.05, ***P < 0.001.

Figure 2

The influence of bedtime on skin barrier related parameters. (A) Hydration, (B) TEWL and (C) Sebum.

Figure 3

Bacterial diversity and composition analysis.(A) Venn diagram on OTU level; (B) the Alpha diversity evaluated index:Sobs index; (C) Ace index; (D) Chao index; (E) Shannon index; (F) Coverage index; (G) Species abundance on phylum level of S0, S1 (H) Species abundance on genus level of S0, S1; (I) Differences of species abundance on genus level of S0, S1; S0: early bedtime group; S1: late bedtime group; difference test method: Wilcoxon rank-sum test, P< 0.05 means significant difference, *P < 0.05, **P < 0.01.

Figure 4

Spearman correlations between facial bacterial abundance and skin physiological parameters; only the top 20 genera in abundance were shown. *P < 0.05, **P < 0.01, ***P < 0.001.