older guys falling asleep.
its funny, I had a 28 year old copilot about 9 years ago...he fell asleep on my leg (an offense that will get you fired at my line).
the new breed of pilots is more interested in the lifestyle of a pilot (travel, women, scuba diving, hobbies etc) than being a good pilot.
A good pilot will make sure he is alert from start to finish of his duty day...and his off duty time is spent making sure that he can be alert on his next duty day.