Sleep duration and chronotype (ie, morningness–eveningness) are associated with increased depression and anxiety risk, but differences in individual sleep needs and lifestyle may mean these sleep parameters do not present the same risk for all individuals. This according to a recent study that explored the mediating role of sleep debt and daytime sleepiness in the relationship between sleep and mental health symptoms in young adults, a particularly vulnerable population. Young adult university students (n=2,218) and young adults from the general population in the US (n=992) provided estimates of actual and optimal sleep duration, and completed validated measures of sleepiness, chronotype, and depression and anxiety risk. Researchers found:

• Sleepiness and sleep debt mediated the relationship between short sleep and depression and anxiety risk in the university sample, while sleepiness mediated these relationships in the general population sample.
• Sleepiness and sleep debt also mediated the impact of evening‐type preferences on depression and anxiety risk in university students, but no mediation of this effect was found in young adults from the general population.