Circadian Rhythms, Sleep Deprivation, and Human Performance - Progress in Molecular Biology and Translational Science - page 172

Figure 7.3 The individual linear slopes of the change in Psychomotor Vigilance Task
(PVT) transformed lapses during 38 h of total sleep deprivation in monozygotic
(MZ; A) and dizygotic (DZ; B) twin pairs. Data for each MZ and DZ twin pair are plotted
together on the abscissa. In each panel, the pairs are ordered by the magnitude of their
impairment (averaged over each pair), with the most resistant twin pair on the left and
the most vulnerable twin pair on the right. The panels reveal substantial differences in
individual responses to sleep deprivation. The intraclass correlation (ICC) revealed
greater similarity within MZ twin pairs than within DZ twin pairs. There was 56.2% of
the total variance in the MZ twins due to variance between pairs whereas only
14.5% of the total variance in DZ twins was due to variance between pairs. Reprinted
with permission from Ref. 182 .
illustrate this point. As mentioned previously, the PER3 VNTR polymor-
phism has been associated with individual differences in sleep homeostatic
and executive performance responses to acute total sleep deprivation. 143,144
We showed that this polymorphism related to individual differences in sleep
homeostatic responses, but not cognitive performance responses to chronic
sleep restriction. 148 By contrast, two recent studies, 167,184 which used