Why are there dates on which we can't hold parties?

Per the Office of Student Life,

"Student organizations are not permitted to host events, programs and activities during Exam Period and rooms are unavailable for reservation during that time.  Large, late night social events are not permitted in the Houses over Head of the Charles Weekend or on nights preceding an administration of the LSAT.  In addition, restrictions may be placed on events during Reading Period if they interfere with residential areas and libraries where exam preparation is underway."

See also: Parties