How To Improve Energy Levels?

Hi, I was just wanting some advice on something. My boyfriend is 20 years old, and he works 50hrs a week as a butcher, but he is always tried, wants to sleep all weekend and ways wakes up tired at 12pm and wants to be asleep again at 6pm, what is the causes of this? Is there anything I can get him to try so he enjoys the quality of life and is enthused to be around me and to be active?