until the small hours of the morning

during early night time hour

See for example, Debates, June 20, 1984, p. 4940. The confusion in this case resulted from the calling of several consecutive recorded votes lasting into the early hours.

[14] In 1925, a committee made a similar recommendation, again without success, on the basis that “Late sittings at night are injurious to the members’ health and do not materially shorten the sessions”.

Now, it was my intention, up until three in the morning, to come here and dazzle you with wonderful statistics, but my learned colleagues have done that, so I don't think it's going to be of much use.

M. whereas the current socio-economic crisis has led to the adoption of an increasing number of laws allowing extended working hours until late in the evening, night work, and work on public holidays and Sundays, and to the infringement of rules governing break and rest periods; whereas some sectors, such as retail services, where most of those employed are women, have been more severely affected and whereas this has had direct negative consequences on working conditions, employees’ health, and on efforts to secure a work-life balance and social cohesion;