LGI1 and hypersomnia: AIE associated with antibodies against leucine-rich glioma-inactivated 1 (LGI1) or contactin-associated protein 2 (CASPR2), and AIE with Ma2 or IgLON5 autoantibodies are the most widely known and studied subtypes in association with fragmented sleep and sleep disorders such as insomnia, hypersomnia and rapid eye movement (REM) sleep behavior disorder (RBD) [2–4].