Flies expressing CanA-14F^{Scer\UAS.T:Hsap\MYC} under the control of Scer\GAL4^elav-C155, where expression is suppressed at the restrictive temperature of 19[o]C, are viable and do not have visible developmental defects. A temperature shift to 30[o]C for 2 days (after 3 days development at 19[o]C) markedly decreases nighttime sleep in control flies and in those from the progeny of the Scer\GAL4^elav-C155; Scer\GAL80^ts.αTub84B x CanA-14F^{Scer\UAS.T:Hsap\MYC} cross in both LD and DD, with no significant difference in their sleep levels before or after the temperature shift. This effect is most pronounced during night time, when control flies and CanA-14F^{Scer\UAS.T:Hsap\MYC}-expressing flies are highly active at 30[o]C.