The national anthem would play, then a test pattern, then static. That was it. No 24-hour anything. If you were up at 2am, the TV could not help you.
You would hear the hiss and know the whole world had gone to sleep except you. We had a Zenith with the clunky dial. My father would fall asleep in his chair and I would creep downstairs to watch the late show.
When the station signed off, the sudden silence was deafening. That white noise is still the loneliest sound I know.