Background: Epilepsy has many co-morbidities which may disturb patient life more than the seizures themselves. Seizures can change the brain both structurally and functionally, manifesting as cognitive and neuropsychological disorders. Roughly 30–40% of epileptic patients suffer from cognition changes. Frequent abnormal neuronal discharge, especially status epilepticus, causes oxidative stress leading to disruption of cognitive function. Methods: This case control study was conducted on 158 epileptic patients and158 apparently healthy individuals as a control group, all individuals were exposed to cognitive function testing via The Montreal Cognitive Assessment, sleep quality assessment by Pittsburgh Sleep Quality Index and evaluation of the serum level of orexin was done. Results: 62% of epileptic patients had cognitive impairment; the best cutoff of orexin in prediction of poor cognition among PWE is ≤195 with sensitivity 85.7%, specificity 91.7%. Conclusions: Our data concluded that the prevalence of cognitive impairment in epilepsy is high; serum orexin level could be used as a predictor for cognitive impairment and sleep disorders in epileptics.