On Monday nights the MBTA sometimes calls it quits before the City Council. Council meetings, filled with long discussions of everything from rent control to softball games, have been known to stretch from 5:30 at night to past 1 a.m.

But claiming that "six-and-a-half hours for a meeting is enough," Vice Mayor Edward N. Cyr sponsored a motion to stop all meeting at midnight.

The council passed the measure, after 20 minutes of debate, one a vote of six to two.

The council's self imposed deadline has already been imposed. Monday's night meeting was shut down at the stroke of midnight. The council will meet again tonight to finish up the week's business.

And that may mean that, in the end, the meetings will last even longer.

"We only did half of our business and now we're going to have to come back Wednesday for another two to three hours," said Councillor Francis H. Duehay '55, who opposed the measure.

So far this year, seven council meetings have lasted past midnight.

According to the Boston City Council's Central Staff, Boston's council meetings usually last between one and two hours. The Somerville City Clerk's Office said Board of Alders meetings usually last between three and four hours.

"The spirit of the rule makes sense," said Mayor Kenneth E. Reeves '72, who voted present. "I do tend to feel that everybody should feel they got to say what they wanted to say."

Councillor William H. Walsh, who supported the measure, said he hoped the deadline would limit "repetitious" discussions.

But Walsh, an independent, added that he suspects the rule could be used for partisan politics.

A vote of six councillors can suspended the rules to sidestep the midnight deadline. The progressive Cambridge Civic Association-backed councillors hold a six to four majority on the council.

Councillor Jonathan S. Myers, who opposed the measure with Duehay, said he doubted the council would always be able to finish its work by midnight.

"It just means we will have that much more work to do at our next meeting," he said.

Duehay said the best way for the council to limit the meetings was to limit the speeches that often dominate the council chamber.

"I feel that the City Council members can handle it by limiting the amount of time they talk," Duehay said.