APOE and Cognitive impairment: NREM: non-rapid eye movement; REM: rapid eye movement; NR: not reported; MCI: mild cognitive impairment; 3MS: Modified Mini-Mental State Examination; OSA: obstructive sleep apnea; AHI: Apnea–Hypopnea Index; MoCA-SA: Montreal Cognitive Assessment – Survey Adaptation; CAP: cyclic alternating pattern; EEG: eectroencephalography; CSF: cerebrospinal fluid; APOE ε4: apolipoprotein E epsilon 4 genotype; SDB: sleep-disordered breathing; ODI: Oxygen Desaturation Index; SaO2: arterial oxygen saturation; TST: total sleep time; PSQI: Pittsburgh Sleep Quality Index; ESS: Epworth Sleepiness Scale.