It's only the first day and already the toil of thinking about complex theories , atoms and molecules is taking its toll.
But this isn't a bunch of new students snoozing in a lecture after a late-night out, these are some of the world's top scientists in Belfast for one of the largest and most prestigious physics conferences in the world.
Almost 600 boffins have descended on Queen's University to take part in the conference, a get-together for the discussion of atomic and molecular physics.
These senior scientists have arrived in Belfast to take part in The International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC), where they will discuss the latest developments in atomic, molecular and laser physics.
Top physicists from 53 countries around the world, including as far afield as the USA, China and Israel, have flown into the city to take part in the week-long series of talks and discussions at the university's Whitla Hall and David Keir buildings.
It is the first time the conference has been held on the island of Ireland, and Belfast is only the third UK city to host the ICPEAC in its 53-year history.
Professor Bob McCullough, who is part of the committee organising the conference at Queen's, said it was quite a coup to secure the event for the university.
"It's really quite a large conference and quite a prestigious one," he said.
He added that while a conference on the collisions between atoms, molecules, ions and electrons may sound obscure, it's a process which has a very significant impact on people's lives.
"It sounds very esoteric but has very important applications. For example cancer therapy is one of the major applications of this area now," he said.
And all the scientists are keen to stress their work does have a place in the 'real world', saying once we understand how something works at its most fundamental level we are better placed to use it to our benefit.
Among the topics under discussion are how ion beams can be used to target radiation in DNA cells; using ultra-fast laser flashes to study bio-molecules and studying anti-matter to better understand the big bang theory.
The conference schedule is jam-packed with talks, discussions and lectures as well as a number of 'poster sessions' where delegates get to show off their work .
But the physicists won't be spending all their time in the lecture theatre - with the conference taking place over the weekend, the boffins have the opportunity to take in some of Northern Ireland's famous sights.
Let's hope they don't get too much fun in the sun, or Monday morning's lectures could have more sleepy heads than usual.