Figure 1. Relationship between serum levels of soluble alpha Klotho (sαKl) and environmental stresses.

Relationships between serum levels of sαKl and (A) sleep duration time and (B) psychological stress. Sleep duration time was classified into three periods: ≥6 hours per day, >4 and <6 hours per day, and ≤4 hours per day. Psychological stress was classified into four stages: almost no stress (None), sometimes feel stress (Sometimes), often feel stress (Often), always feel stress (Always). Data are sample minimum, lower quartile, median, upper quartile, and sample maximum. n = 80, *P < 0.05 versus subjects whose sleep duration time were ≥6 hours per day.