Serotonin regulates critical cognitive functions including sleep, anxiety and mood amongst others. A subset of psychedelics activate the serotonergic system in the brain by either increasing serotonin at the synaptic cleft or directly activating serotonin receptors on a variety of cells. Due to the diversity of neurons (inhibitory versus excitatory) and serotonergic receptors it makes imaging studies (e.g. fMRI) difficult to interpret and understand the effect of psychedelics. We are investigating the role of serotonin and psychedelics in key brain structures at the single neuron and at the circuit level to look at the underpinnings these substances have on sleep, memory and anxiety.