Back in the early 80s I trained as a nurse and stayed working at the same hospital until the early 90s. The hospital was knocked down about 20 years ago along with a neighbouring one as they merged and a new PFI hospital was built.
Each floor of the hospital had three wings, east, central and west and each wing had two nightingale wards. It was only a three story hospital. The way the building was set out meant that if you were at the nurses station in ant if the wards, you could see the lifts. Hospitals were a bit quieter at night then in the sense that in the early hours, whilst you may have some very ill patients, you didn't get some of the night admissions/late night moves of patients that we see nowadays so the lifts, corridors etc would be very quiet. Also for the last 18 months I worked there, we no longer had an A&E, it was centralised on the other hospital site, so we didn't even get emergency admissions at night.
However, on one wing, you'd often hear the lift start to whirr and could hear it coming up but slowly, much slower than normal, see the arrow light lit up, arrive, the doors open, no one come out, then the door close, and it would go down again. I always got a huge sense of dread when it did this as did others. It was an old lift and it's design meant it would sit at the last floor it had been at until someone had pressed the button on one of the other floors. It would do this several times over one night for no apparent reason and then not at all on the following nights. Our rotas were a six week rotation of which one week was a week of nights, and this wouldn't happen all the time but enough for us all to notice. We'd reported it to security on more than one occasion in case someone was mucking around, they found no one, and also to estates in case there was a fault, no fault was ever found.