Urinary 8-hydroxydeoxyguanosine levels and psychological reactions after sleep deprivation.

The aim of this study was to investigate whether changes in urinary 8-hydroxydeoxyguanosine (8-OH-dG), an oxidative stress indicator, occur or not, and how psychological reactions change, after one night of sleep deprivation (SD) and after 7 hour recovery sleep opportunities during three recovery days. Twenty healthy subjects participated in this study. We measured their urinary 8-OH-dG levels and psychological reactions using the Profile of Mood States (POMS) for 5 days: on the baseline day, the post-vigil day, and on 3 recovery days after SD. The urinary 8-OH-dG levels and subscale scores of POMS were analyzed using repeated analysis of variance (ANOVA). In the psychological reactions, the values of Vigor on the post-vigil day and 2nd recovery day were significantly lower than on the baseline day. Fatigue and confusion on the post-vigil day were significantly higher than on the baseline day, and on the 1st and 2nd recovery days were relatively higher compared to the baseline day but returned to baseline level on the 3rd recovery day. The urinary 8-OH-dG levels did not change significantly after SD, on the post-vigil day or on the 3rd recovery days. These results suggest that the effect of one night of SD on psychological reactions continued for 2 or 3 days, and SD might not influence urinary 8-OH-dG levels despite marked changes in psychological reactions.

Recovery of cognitive performance and fatigue after one night of sleep deprivation.

OBJECTIVES: The aim of this study was to investigate how subjective sleepiness, mood states, simple and high-order cognitive performance change after one night of sleep deprivation (SD) and recover to after 7 h normal recovery sleep opportunity during three recovery days. METHODS: Ten healthy subjects participated in this study. We measured their subjective sleepiness, mood states and their performances of 2 simple tasks and 4 high-order cognitive tasks twice a day for 5 days, on the baseline day, post-vigil day and 3 recovery days after SD. This study was conducted considering each participant's motivation for task, learning effect and diurnal variation of performance. RESULTS: The performances of simple tasks such as addition or short-term memory were not reduced after SD and were the poorest on the baseline day, and improved gradually; however the high-order cognitive performances were at their lowest on the post-vigil day and needed 2 recovery sleep opportunities to return to the baseline level. Fatigue and confusion in mood states and subjective sleepiness were also at their lowest after SD. Subjective sleepiness nearly recovered to the baseline level on the 1st recovery day, but fatigue and confusion reached the baseline levels on the 2nd recovery day. CONCLUSION: These results suggest that cognitive deterioration and the recovery process may differ between simple task performance and high-order cognitive task performance, which needed 2 ordinary sleep opportunities to recover to the baseline level, and the change of subjective mood states were also different for each mood.

[Characteristic patterns of fatigue feelings on four simulated consecutive night shifts by "Jikaku-sho shirabe"].

The aim of the present study was to reveal characteristic patterns of fatigue feelings on consecutive night shifts by a questionnaire for work-related fatigue feelings "Jikaku-sho shirabe". Ten healthy males (Mean +/- SD: 22.9 +/- 3.2 years old) participated in the experiment. Participants were required to attend the laboratory for nine consecutive nights under the following conditions: adaptation sleep (0:00-7:00), simulated day shift (10:00-18:00), baseline sleep (0:00-7:00), directly followed by four simulated night shifts (22:00-9:00) and the subsequent daytime sleep (12:00-18:00), three recovery nights (0:00-7:00) and two simulated day shifts (10:00-18:00). During each simulated shift, participants were required to complete an English transcription task (30 min), a performance test battery (20 min) and break (10 min) every hour. Fatigue feelings were evaluated by "Jikaku-sho shirabe", which was proposed by the Industrial Fatigue Research Committee of the Japan Occupational Health in 2002. This questionnaire consists of 25 subjective fatigue symptom items that are categorized into 5 factors: feeling of drowsiness (Factor I), feeling of instability (Factor II), feeling of uneasiness (Factor III), feeling of local pain or dullness (Factor IV), and feeling of eyestrain (Factor V). For each item, respondents are requested to estimate the intensity of the feelings as "Disagree at all," "Agree scarcely," "Agree slightly," "Agree considerably," and "Agree strongly." These five intensities were assigned scores of 1 to 5 points, respectively. Hierarchical cluster analysis suggested that there might be at least three variation patterns of fatigue feelings on the consecutive night shifts (i.e. Clusters A, B and C). On the basis of subjective fatigue symptom items of each cluster, the patterns in Clusters A, B and C might reflect the loads of the reticular activating system, musculoskeletal and central nervous systems, and limbic system, respectively. For Clusters A and C, significant improvements were observed with the increase of the number of night shifts (F(11,99)=3.07, p<0.01, F(11,99)=3.37, p<0.01, respectively). On the other hand, Cluster B deteriorated with the progress of the simulated night shifts. Taken together, we suggest that the characteristic patterns of fatigue feelings on consecutive night shifts might represent dissociation among the feelings induced by several loads.