The suprachiasmatic nucleus (SCN) is a principal circadian pacemaker synchronising our daily routines to environmental cues, such as the day/night cycle. The SCN relies on an endogenously generated electrical output rhythm as one of its timekeeping mechanisms. This consists of higher neuronal spontaneous activity during the day, which then silences during the night. Excitation of the SCN neurons is tightly regulated by two-pore domain potassium channels (K2P). These K2P channels play a role in establishing resting membrane potential and have been implicated in driving the excitability of SCN neurons. TRESK – calcium regulated leak two-pore potassium channels are highly enriched in the SCN compared to other brain regions. We employed a TRESK knock-out mouse model to assess alterations in SCN molecular changes, behaviour output and electrical properties.