It had been a busy day for Roger. Not only was he exhausted from the crap he went through the night before, but he had been busy ever since he got into work. There was a dead body found in the Department of Mysteries, and as soon as he got to his desk, there was a memo waiting for him to go meet Gaskin.
Roger and Potter were assigned the case, and they were busy all day. They had to examine the crime scene, talk to security staff, get the body to the morgue at St. Mungo's. It was only the first day, but Roger still wasn't sure yet what had killed the man or why he was there.
He was at his desk now, with stacks paper work on his desk of visitor logs with pictures, going back a year. This was his brilliant idea, so Roger had to go through it. But he needed a break, or coffee or something. He was ready to fall asleep.
He needed a break anyway, so he extended his coffee break out into a walk. Roger was already feeling better when he took his first drink of coffee. He was walking back towards his desk when he noticed Cho at hers... asleep.
He remembered how he'd promised Cho earlier that he wouldn't wake her up if he noticed she was asleep. But he also knew that if one of Cho's superiors found her that way first, it wouldn't be good. So Roger took a detour in his walk, and went over to lean against Cho's desk, and knocked on the top of it, loud enough for Cho to hear.