Table 1.
Descriptives.
Figure 1.
Observed ratings of subjective sleepiness on the Karolinska Sleepiness Scale (KSS) plotted against time of day (at home base) with a LOWESS line indicating approximate means for home base time zone (left) and other time zones (middle) with the overall distribution of time zones for all ratings (right).
KSS ratings have had a random jitter applied to better illustrate the distribution at different levels.
Figure 2.
Observed sleep probability across time of day for the home base time zone and westward time zone shifts (left) and eastward time zone shifts (right).
Table 2.
Model fitting summary.
Figure 3.
Residuals (observed ratings-predicted sleepiness) plotted against predicted KSS (left), time awake (middle) and time of day (right) for the best model with assumed default phase of C (model 5c, top) and circadian type adjusted phases of CT (model 6d, bottom) with a LOWESS line indicating potential systematic bias in predictions.
Figure 4.
Observed, predicted and generated sleep.
The top panel shows the proportion of observed 5 minute segments (n = 577969 for 118 subjects with sleep data) with observed duty, observed sleep, sleep generated by the TPM (with default thresholds) and predicted sleep based on the fixed part of a multilevel mixed effects logistic regression (equation 15) with observed sleep as the dependent variable and generated sleep as the predictor. The middle panel shows observed sleep for different circadian types. The bottom panel shows the output from three different sleep generators. The default sleep generator used a fixed phase of C (p = 16.8) for all subjects and threshold of S+C+U at 8.38 for falling asleep and 11.38 for waking up. Default sleep generator with adjusted phase use individually adjusted phases (p = 14.61 h, 15.28 h, 15.95 h, 16.62 h) depending on rated circadian type (morning type – extreme evening type). The new sleep generator use adjusted phases of CT with a threshold for falling asleep of S+C<8 and waking up S+C>13.
Figure 5.
Predicted probabilities as a function of alertness score (SB+C+U) based on equation 17.
Left panel shows probabilities for specific outcomes (KSS = 6–9) and right panel shows probabilities for severe sleepiness (KSS≥7) with reference limits accounting for 75% and 90% of subjects (below the line) in addition to the average subject (i.e. 50% reference limit).
Figure 6.
Empirical Bayes’ estimates of all subjects circadian phase based on equation 13.
Table 3.
Model summary of varying daily acclimatization rates.