From Facilities Management:
Northbound I-405 (all lanes) will be closed between Wilshire Boulevard and Moraga Drive from midnight until 5 am on the mornings of Thursday, December 5th and Friday, December 6th. Southbound I-405 will remain open during this time.
When: Midnight-5 am on Thursday, December 5th and Friday, December 6th
Where: I-405 Northbound between Wilshire and Moraga
And note that the friendly folks on the 405 project often start blocking things as early as 10 pm.