Overnight commuters on the Nos. 4, 5 and 6 trains will have to find an alternative this week as the line undergoes the MTA's Fastrack repair program.

There will be no trains on the line between Grand Central-42 St. and Atlantic Ave.-Barclays Center from 10 p.m. to 5 a.m. The repairs will last from Monday night through Friday morning.

To make up for the change, overnight No. 3 train service will be extended into Brooklyn, making all No. 4 train stops between Atlantic Avenue and New Lots Avenue.