CLOCK and Alzheimer disease: Indeed, although clock genes seem to be able to control mitochondria function (de Goede et al., 2018) as well as synaptic plasticity and memory (Eckel-Mahan and Storm, 2009), it remains to be established if the presently observed loss of circadian variation of synaptic properties and memory is either due to a direct effect of clock genes that are altered in AD (Sheehan and Musiek, 2020) or instead to altered wake-sleep cycles also present in AD (Colwell, 2021) that can affect mitochondria (Smith and Musiek, 2020) as well as synaptic plasticity and memory (Walker and Stickgold, 2006).