To qualify to log this cache then you must have found and logged 10 distinct caches which are night caches, or an event specifically designed as a night cache.
Just to qualify, its not night caches that you've placed, its ones that you've either found or attended.
Caches can be found at any time, and it doesn't matter if they're still active or have been archived. Not all night caches have the night cache attribute, so dont rely on searching for the attribute with the cache box and the crescent moon.
Evening events dont qualify unless they are night caching events, so they were set up specially for walking round in the dark finding caches (eg the night cache events for the megas or the halloween events)
You can sign the log in the cache for this challenge at any time and log a 'note' to the cache page, mentioning you signed the log.
But you may not log a find until you have completed the requirements (this way you don't have to go back to sign after you complete the requirements!).
Once you complete the requirements, edit your log, change it to found, and change the find date to the date you completed the requirements and list the required information.
I will be checking the 10 caches, so no sneaking in a cache that has the word 'night' in there but isn't a proper night cache.
For example, here are my 10....
Mega Adventure After Dark on 29/Jul/2010 - http://coord.info/GC286PK
Grabbed by the Ghoulies '10 on 31/Oct/2010 - http://coord.info/GC2FTJ7
Mega 2012: On the Trail of the Pendle Witch on 09/Aug/2012 - http://coord.info/GC3F462
LED Astray by Semaphore on 21/Aug/2010 - http://coord.info/GC2CCR5
Green Lantern on 21/Aug/2010 - http://coord.info/GC2CCR9
Merry Men - Robin Hood - Night Cache on 23/Jul/2011 - http://coord.info/GC303HQ
The Nichts Are Fair Drawin' In on 30/Oct/2011 - http://coord.info/GC36KM9
Dem Bones on 21/Aug/2010 - http://coord.info/GC2CCRB
LED Astray by a Predator on 21/Aug/2010 - http://coord.info/GC2CCRX
A Walk in the Park... on 19/Nov/2010 - http://coord.info/GC2HJA6