Night-time hyperactivity makes up part of the unique behavioural profile of autism spectrum disorder (ASDs). Recent studies on zebrafish revealed that loss-of-function mutations in autism risk genes (e.g. CNTNAP2) lead to a reduction in GABAergic neurons in the hypothalamus. GABAergic cells are sleep promoting and play an important role in the regulation of sleep-wake cycle. There are different subtypes of GABAergic cells, such as galanin-positive and MCH-positive neurons. In this project, we are going to investigate what subtypes of GABAergic cells are lost in autism mutants, using in situ hybridisation and basic microscopy. Significant difference in the amount of cells present in the wild-type and mutant will be expected.