Dysfunctional intrinsically photosensitive retinal ganglion cells, reduction of VIP immunostaining in the SCN, and disrupted rhythms in SCN electrophysiology, cortisol, melatonin, body temperature, heart rate and metabolic outputs (Smarr et al., 2019; Fifel and Videnovic, 2020; Colwell, 2021) provide evidence for circadian disturbances in HD mice at levels of clock input and output, thus also affecting molecular clockwork in vivo, resulting in overt behavioural and peripheral rhythm disturbances. Here, CLOCK is linked to Huntington disease.