IGLON5 and insomnia measurement: 1999). The microstructural elements of sleep, such as sleep spindles and K complexes, are generated by the thalamus (De Gennaro and Ferrara 2003; Halász 2016). So, it is not surprising that in thalamic variants of CJD, sleep structure is highly disrupted and insomnia may be the first sign of the disease (Sun et al. 2021). Sleep problems can sometimes be so severe that they can mimic anti‐IgLON5 disease (Hongo et al. 2019).