Reaction of sleepiness indicators to partial sleep deprivation, time of day and time on task in a driving simulator – The DROWSI project
Journal of Sleep Research. 2009-12-28; 19(2): 298-309
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1. J Sleep Res. 2010 Jun;19(2):298-309. doi: 10.1111/j.1365-2869.2009.00796.x. Epub
2009 Dec 28.
Reaction of sleepiness indicators to partial sleep deprivation, time of day and
time on task in a driving simulator–the DROWSI project.
Akerstedt T(1), Ingre M, Kecklund G, Anund A, Sandberg D, Wahde M, Philip P,
(1)Stress Research Institute, Stockholm University, Stockholm, Sweden.
Studies of driving and sleepiness indicators have mainly focused on prior sleep
reduction. The present study sought to identify sleepiness indicators responsive
to several potential regulators of sleepiness: sleep loss, time of day (TOD) and
time on task (TOT) during simulator driving. Thirteen subjects drove a
high-fidelity moving base simulator in six 1-h sessions across a 24-h period,
after normal sleep duration (8 h) and after partial sleep deprivation (PSD; 4 h).
The results showed clear main effects of TOD (night) and TOT but not for PSD,
although the latter strongly interacted with TOD. The most sensitive variable was
subjective sleepiness, the standard deviation of lateral position (SDLAT) and
measures of eye closure [duration, speed (slow), amplitude (low)]. Measures of
electroencephalography and line crossings (LCs) showed only modest responses. For
most variables individual differences vastly exceeded those of the fixed effects,
except for subjective sleepiness and SDLAT. In a multiple regression analysis,
SDLAT, amplitude/peak eye-lid closing velocity and blink duration predicted
subjective sleepiness bouts with a sensitivity and specificity of about 70%, but
were mutually redundant. The prediction of LCs gave considerably weaker, but
similar results. In summary, SDLAT and eye closure variables could be candidates
for use in sleepiness-monitoring devices. However, individual differences are
considerable and there is need for research on how to identify and predict
individual differences in susceptibility to sleepiness.
PMID: 20050992 [Indexed for MEDLINE]