Hi,its Been Happening For Some Time Now,I Cannot Stay Awake

Hi,its been happening for some time now,I cannot stay awake in the evening,its irritating my missus,as I carnt sit through a movie,without nodding,my normal working week involves bike riding early to work,its a 20 mile round trek,so I'm pretty fit,I even get up early at weekends for no reason,around 6am,I have no trouble sleeping,but around 5 to 7 hrs at the most,diet good,not sure how to stay awake,its a nightmare if we go to friends homes,as I battle to stay awake,its embarrassing.