Ah, now 24x7 access is really a pretty recent thing. It was just one of those things that seemed impossible, like pizza delivery or Sunday opening, back in the 70s & 80s. But most Uni Libraries would be open to somewhere between 10-midnight in term, and maybe 6pm outside of it. The whole point of Sundays was to be bored out of your skull with nothing to do on you day 'off'.