Song, Sun, Yang, Zhang,Yang, Bai (2015)

Methods:

Quoted text from the Methods section:

All subjects in sleep deprivation group had blood drawn for cortisol level measurement at 8 a.m. on Day 8 as the baseline and 8 a.m. on Day 9 after-deprivation measurements respectively for comparison. The moment when the 24 h ended, all subjects in sleep deprivation group and control group were instructed by research staff to run group test with Military Personnel Mental Disorder Prediction Scale for mental health measurements.

Translation:

The people in the sleep deprivation group had their blood taken at 8 a.m. on the first day to check their normal cortisol levels, and then again at 8 a.m. the next day after not sleeping, so the researchers could compare the two. After 24 hours, everyone in both groups took a mental health test called the Military Personnel Mental Disorder Prediction Scale, with the researchers helping them.

Introduction:

Quoted text from the Introduction:

Therefore, the aim of this study was to investigate effects of cortisol level change induced by sleep deprivation upon mental status and to determine the optimum cut-off value of serum cortisol as a biochemical indicator to predict mental status change in servicemen.

Translation:

This study wanted to find out how losing sleep affects stress hormone levels (cortisol) and mental health in soldiers. It also tried to figure out the specific cortisol level that could predict changes in mental health.

Results:

Quoted text from the Results:

Kruskal–Wallis H test results showed that the total score of mental disorder prediction and factor scores of psychosis, depression, mania, neurosis, personality disorder, lack of social support, introversion personality, growing experience were significantly different among the sleep deprivation group, control group and military norm (p < 0.05).

Translation:

The tests showed that the sleep-deprived group, the control group, and average soldiers had different scores on mental health problems. Sleep deprivation affected scores for things like depression, mania, personality problems, feeling socially unsupported, and being more introverted.

Discussion:

Quoted text from the Discussion:

In this study, the significantly increased total score of mental disorder prediction and factor scores of mania and personality disorder in sleep deprivation group are consistent with extensive evidence that sleep deprivation as a typical endogenous stress (McEwen, 2006) could significantly affect mental health in servicemen (Kamphuis et al., 2012, Sloan, 2011).

Translation: The researchers found that soldiers who didn’t sleep scored higher on mental health problems, especially for mania and personality issues. This matches other studies showing that lack of sleep is a type of stress that can hurt mental health.

Future research could compare men and women or include people from different age groups to see if sleep deprivation affects cortisol and mental health in the same way. 

I found the statistical tests and graphs in the results section difficult to understand because I’m not familiar with terms like “Wilcoxon rank sum test” or “ROC curve.”