Comparison of the sleep ratio revealed a significant difference between genotypes (F(2,166) = 3.654, p = 0.028), where homozygous vmat2 mutant larvae exhibited a significantly higher sleep ratio than wild types (0.407 ± 0.017 vs 0.332 ± 0.025, p = 0.049) (Fig 1G), indicating a day-time hypersomnia in mutants. The gene discussed is SLC18A2; the disease is hypersomnia.