Chronotype in patients with epilepsy: A controlled study in 60 subjects with late-onset focal epilepsy

Studies based on self-administered questionnaires indicate that most patients with epilepsy are morning-oriented. We aimed to investigate chronotype in patients with epilepsy with late-onset focal epilepsy by combining subjective data with dim light melatonin onset (DLMO) as an objective marker of the circadian phase. Sixty adult patients (mean age 46.5±13.8; 27 males) with late-onset focal epilepsy under pharmacological treatment were prospectively studied. Subjective chronotype was determined using the Morningness-Eveningness Questionnaire (MEQ) and circadian phase through analysis of salivary melatonin secretion, considering 3pg/ml as the dim light melatonin onset (DLMO) threshold. The mean MEQ score was significantly higher in the patients with epilepsy than in the controls, and significantly, more patients had a MEQ score indicative of the morning type (50.0% vs 30.0%, p=0.02). However, no significant differences were found in mean time of DLMO (21:38±01:21 vs 21:26±01:03; p=ns), and DLMO time was in the range indicative of an intermediate chronotype in both patients and controls. Sleep onset and sleep offset phase angles were significantly shorter in the patients. Patients whose global MEQ score identified them as morning types were significantly older than those with an intermediate or evening chronotype, and they had less social jet lag. No difference in epilepsy features and treatments was found between morning-oriented and nonmorning-oriented patients. Our analyses showed that the patients with epilepsy tended to be morning-oriented and to perceive themselves as morning types, even though this was not reflected in their DLMO values which did not differ significantly from those of controls and mostly fell within the intermediate chronotype range. Several factors may considerably influence subjective chronotype. We speculate that, in patients with epilepsy, the disease itself, prompting certain lifestyle choices, including a regular sleep schedule and early bedtime, may induce morning orientation and a morning-type self-perception.