|Budget Amount *help
¥3,740,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
[Introduction and method] The purpose of this study was to evaluate increase of stress and fatigue by sleep deprivation (SD). Six healthy college male students without sleep problem were recruited into our study. The measurements were Visual analogue scale (VAS) and Karolinska sleep scale (KSS) as an index of subjective sleepiness and Psycho-vigilance test (PVT) which measures simple reactive performance. To evaluate biomarkers of the SD stress, we collected saliva to assess its acidity and concentration of Chromogranin A(CgA) corrected by total concentration of protein in the sample. In addition to those measurements, total plasma oxidant/antioxidant capacity was measured by FRAS4(H&D srl, Parma, Italy). The d-ROM is chromogen which loose color by oxidant produced by any kind of stress. The BAP which utilizes the phenton reaction correlates with the antioxidant capacity. We carried out these measurements four times at 8: 00 and 16: 30 the day before the SD and at that same time on the
next SD day.
[Results] The results of the VAS and KSS indicated significantly increasing sleepiness due to the SD, while reactive performance level by PVT was maintained in the SD situation. The salivary acidity showed high level during all sessions and no significant change by the SD stress, while the level of CgA changed by the SD. As the former studies had already reported, the concentration of CgA had a circadian rhythm, especially in our subjects who were not able to keep awake completely and took a short recovery sleep before early morning. The CgA essentially increases in early morning and decreases in evening. That is, the level of CgA during the SD day in the subjects who took a short sleep before morning decreased in the evening like that on the day before SD. Meanwhile, in the subjects who never slept at all in the night of SD day, the level of CgA did not decrease in evening on the SD day.
In only two subjects, the level of d-ROM on the SD day showed substantially higher than that on the day before the SD. However, four subjects including the former had the higher levels of d-ROM in the evening on the day of the SD than that in the morning on that day. In four subjects, the level of BAP was higher in the morning on the day of SD than that in the evening on the day before the SD. In three out of the four subjects, the BAP level had already decreased in the evening on the day of the SD.
[Discussion] It was confirmed that subjects' sleepiness by the SD was demonstrated through VAS and KSS, while the subjects did not show impaired performance. It was reaffirmed that subjective sleepiness did not correlate to physical sleepiness as it had been pointed out by Franzen, et. al.(2008).
In this study we could indicate the possibility that the antioxidative capacity transiently increased during and after the SD could suppress the harmful effect of increasing oxidative stress by the SD and that the increased antioxidative capacity could subside within a day. It is also suggested that the antioxidative capacity could vary from individual to indivisual. It was also suggested that the CgA could be a sensitive and useful biomarker of psychological stress by SD. Less