When Parliament is sitting, the Commons normally meets on Mondays at 2.30pm and on Tuesdays, Wednesdays and Thursdays at 11.30pm. Fridays are normally reserved for constituency business except on allotted days for the consideration of private members' Bills. On these days, business starts at 9.30am.
The length of the day is governed by the 'Moment of Interruption'. This is the time when the occupant of the chair rises to put the questions that will dispose of the day's business. The disposal of business is followed by a half-hour adjournment debate. So the normal close of proceedings - when the House rises - is 30 minutes after the Moment of Interruption, allowing for the time taken by any votes.
On Mondays, interruption takes place at 10pm (House rises at 10.30pm). On Tuesdays and Wednesdays it is at 7pm (House rises at 7.30pm) and on Thursdays it is at 6pm (House rises at 6.30pm). When the House sits on a Friday, interruption takes place at 2.30pm and the House rises at 3pm.
Sitting in accordance with such a strict timetable, and for the most part during daylight hours, is something of an innovation for the House. In the past, non-Friday sittings always started at 2.30pm and could continue until well into the night. On occasion, the following day's business was lost because MPs had not risen by 2.30pm on the day following the start of a debate.
The first day back after a recess has Monday sitting hours.