"Nocturnal activity" refers to activities or behaviors that take place predominantly during the night.
Sentences with «nocturnal activity»
They had agreed to remain completely unaware of the results — performing what are called «blind» analyses — until mid-June, when all would suddenly be revealed in a frenzy of nocturnal activity. (scientificamerican.com)
The team found that the ancestors of simian primates — such as gorillas, gibbons and tamarins — were among the first to give up nocturnal activity altogether. (sciencedaily.com)
Based upon the time of your response, looks like you have other nocturnal activities your busy with... (religion.blogs.cnn.com)