The P{dmpi8UP} transgene has been modified to include a premature stop in the ORF of dyw.
Males and females carrying P{dyw-STOP.dmpi8UP} (in a per01 background) show similar levels of daytime sleep under 12:12 hour light:dark conditions and similar levels of sleep under constant light compared to males and females carrying P{dyw-STOP.dmpi8WT} (in a per01 background).