Cognition was assessed using Minimental state examination (MMSE), Trail making tests A and B (TMT) tests, P300 and quantitative electroencephalography (QEEG) sleepiness was assessed using Epworth Sleepiness Scale (ESS), Karolinska sleepiness scale (KSS) and QEEG also polysomnography (PSG) was done for all participated subjects

*The study is a case control study included 40 subjects, divided into 20 cases suffering from Excessive daytime sleepiness and 20 healthy control group.

all participants were subjected to:

1. Careful history taking and Complete neurological examination.

2. Initial assessment of cognition and sleepiness by two scales which were done once before sleep: Epworth Sleepiness Scale (ESS) and Minimental state examination (MMSE)

3. Scales and neurophysiological studies done before and after sleep:Karolinska sleepiness scale (KSS), Trail making tests A and B (TMT), P300, and QEEG

4. Polysomnography (PSG)

   • EEG was recorded for 20 minutes duration before and after sleep recording. In each EEG recording, alpha attenuation test (AAT) was done after 10 minutes of recording basal resting EEG, then the absolute power of 5 electrodes (CZ, T3, T4, T5, T6,) were studied in the following frequency bands: delta (0.5-3Hz), theta (4-7 Hz) and also the absolute power of (O1, O2) were studied in delta, theta and alpha (8-12 Hz) bands.

Inclusion Criteria:

• The age ranges from 18 to 60 years. The age of all included subjects was 31-58 yrs old.
• The body mass index (BMI) range is 24.97-39.06 kg/m2 in patients and 23.40-43.0 kg/m2 in control group.
• Patients suffering from excessive daytime sleepiness symptoms according to the International Classification of Sleep Disorders definitions.

Exclusion Criteria:

• Patients suffering from EDS secondary to any sleep disorder other than sleep disordered breathing.
• Chronic debilitating disease as diabetes mellitus , hypertension or hyper- or hypo-thyroidism.
• Medications that could affect attention or vigilance as Benzodizipines, anti-psychotics or anti-epileptics.

20 patients suffering from EDS 20 healthy subgects