Figure 1
The average light intensity in the Czech Republic (black line) and in Svalbard (blue line) during the 24 h of polar day. The light intensity is plotted on logarithmic scale.
Figure 2
Activity rhythms of subjects in Czech Republic (CZE) and in Svalbard (SVB). A) Mean daily activity of eight subjects in the Czech Republic and in Svalbard. The activity was recorded by MotionWatch for 12 days and displayed as a mean ± SEM in 30 min bins over 24 h. For clarity, part of the day (00:00 to 7:00) was re-plotted. In the Czech Republic, the activity counts are represented by black dots and a black line, and in Svalbard by blue boxes and a blue line. B) Activity acrophase plotted for each subject. Black dots represent the acrophase for each subject in the Czech Republic; blue boxes present the acrophase in Svalbard.
Figure 3
Sleep parameters in the Czech Republic (CZE) and in Svalbard (SVB). A) Fall-asleep time for each subject in the Czech Republic and in Svalbard. B) Wake-up time for each subject in the Czech Republic and in Svalbard. C) Sleep duration for each subject in the Czech Republic and Svalbard.
Figure 4
Daily profiles of melatonin levels in saliva in the Czech Republic (CZE) and in Svalbard (SVB). Melatonin levels were detected in saliva in 24 h profiles and expressed as mean ± SEM in pg/ml (n = 8). Black boxes and a black line represent melatonin levels in the Czech Republic and blue circles and blue lines represent melatonin level in Svalbard.
Figure 5
Cosinor analysis in melatonin daily rhythm. A) Melatonin acrophase plotted for each subject in the Czech Republic (black dots) and in Svalbard (blue boxes). B) Melatonin amplitude plotted for each subject in the Czech Republic (black dots) and in Svalbard (black boxes).
Figure 6
Individual and group clock gene expression in oral mucosa. 1) Per1, 2) Nr1D1, and 3) Bmal1. a) Cosinor analysis of the group means ± SEM 24-h rhythms in Per1, Bmal1, and Nr1D1 gene expression. b) Individually plotted clock gene expression in the Czech Republic. c) Individually plotted clock gene expression in Svalbard. Relative gene expression is displayed in % of maximal value of its expression. Significant rhythms (P < 0.05 for Per1, Nr1D1) are indicated by a solid line; non-significant rhythms are indicated by a dotted line. The group averages are means ± SEM.
Figure 7
The differences in amplitudes and acrophases for individual clock genes’ profiles in the Czech Republic and in Svalbard. 1) Individually plotted amplitudes compared by paired Student’s t-test. 2) Individually plotted acrophases compared by paired Student’s t-test. A) Per1, B) Bmal1, and C) Nr1D1. The dots represent the values in the Czech Republic and the squares represent the values in Svalbard.