Experience and limited lighting may affect sleepiness of tunnel workers - Lykouras, Dimosthenis; Patouchas, Dimitrios; Sampsonas, Fotis; Faliagka, Evanthia; Spiropoulos, Kostas; Karkoulias, Kiriakos; Lakoumentas, John; Tranou, Magdalini-Konstantina; Tsakalidis, Athanasios (2017)