 As such, a person experiencing an en bloc blackout may not appear to be doing so, as they can carry on conversations or even manage to accomplish difficult feats.It is difficult to determine the end of this type of blackout as sleep typically occurs before they end, although it is possible for an en bloc blackout to end if the sufferer has stopped drinking in the meantime.Fragmentary blackouts are characterized by a person having the ability to recall certain events from an intoxicated period, and yet being unaware that other memories are missing until reminded of the existence of those 'gaps' in memory.