SLEEP BREATHING PHYSIOLOGY AND DISORDERS • REVIEW Excessive daytime sleepiness and fatigue in neurological disorders Michelangelo Maestri 1 & Andrea Romigi 2 & Alessandro Schirru 1 & Monica Fabbrini 1 & Sara Gori 1 & Ubaldo Bonuccelli 1 & Enrica Bonanni 1 Received: 15 February 2019 /Revised: 6 August 2019 /Accepted: 8 August 2019 # Springer Nature Switzerland AG 2019 Abstract Excessive daytime sleepiness (EDS) and fatigue are some of the most frequent symptoms in neurological diseases and could impact on quality of life by increasing the risk of accidents and generally affecting daily life activities. In this review, we will examine the variety of causes responsible for EDS in neurological diseases, including nocturnal sleep alterations, CNS patho- logical abnormalities with alterations in arousal and/or REM regulation systems, circadian rhythms disorders, drugs, and comor- bid psychiatric or primary sleep disorders. Among neurological diseases, epilepsy, dementia, Parkinson disease, multiple scle- rosis, and myotonic dystrophies represented a model for these interactions between EDS and neurological diseases. A complete diagnostic workup in neurological patients with EDS should be undertaken since EDS can worsen many different aspects such as psychiatric symptoms, cognitive deficit, and in some cases, the severity of the neurological disease per se. Moreover, quality of life and risk of accidents are dependent on EDS. An individualized approach to this symptom in neurological patients should be considered with a focus on modifiable causes such as SDB, psychiatric comorbidities, and drugs. When considering EDS and fatigue in neurological diseases, close attention to lifestyle and sleep hygiene is advisable. A critical review of ongoing pharma- cological therapy should not be overlooked. Possible diagnosis and treatment of SDB should be always considered. Keywords Fatigue . Excessive daytime sleepiness . Parkinson disease . Epilepsy . Headache . Dementia . Myotonic dystrophies Introduction Excessive daytime sleepiness (EDS) is one of the most fre- quent symptoms in neurological diseases, which could impact on quality of life by increasing the risk of accidents and gen- erally affecting daily life activities. Sleepiness is defined as “the inability to stay awake and alert during the major waking episodes of the day, resulting in periods of irrepressible need for sleep or unintended lapses into drowsiness or sleep” [1], while on the other hand, fatigue is considered as “a reversible decline in motor and cognitive capacities associated with decreased motivation and increased need to rest” [2]. Fatigue is even more difficult to define and usually includes rapid inanition, persisting lack of energy, ex- haustion, physical and mental tiredness, and apathy [3]. Fatigue represents a symptom widely reported by primary care patients (6 to 45%). Even if the increasing interest in clinical practice and research about fatigue is demonstrated by the large number of publications in the last decade, fatigue is still underrecognized [4]. There are a variety of causes responsible for EDS in neu- rological diseases that could interact with one another with a multiplicative effect and progressively exacerbate the patient condition: (i) sleep alterations which include qualitative and quantitative sleep deficiencies and fragmented sleep, (ii) CNS pathological abnormalities with alterations in arousal and/or REM regulation systems, (iii) circadian rhythms disorders, (iv) drugs, and (v) comorbid psychiatric or primary sleep dis- orders [5–7] (Fig. 1). From a methodological point of view, excessive daytime sleepiness has been evaluated in neurological diseases using different measures. Most commonly, a standardized question- naire such as the Epworth Sleepiness Scale has been used, but in many epidemiological surveys, single questions were also employed. Moreover, neurophysiological tests, mainly the Multiple Sleep Latency Test (MSLT) and Maintenance of This paper was presented in a Satellite Course at the Italian National Sleep Meeting (AIMS) held in Taormina on October 4–6, 2018. * Michelangelo Maestri m.maestri@ao-pisa.toscana.it 1 Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Via Roma 67, 56126 Pisa, Italy 2 Sleep Medicine Center, IRCCS Neuromed, Pozzilli, IS, Italy Sleep and Breathing https://doi.org/10.1007/s11325-019-01921-4