In Pathfinder the spells Sleep and Deep Slumber both have caps on how many Hit Dice worth of creatures they can affect, and this limit doesn't increase with level.
For some reason I recall seeing either an archetype, feat, spell or other ability that raises this HD cap or otherwise allows sleep spells to affect more creatures. Of course, now I can't find it by searching (I must have just dreamed the whole thing...). I know the Heavens Oracle does something similar to this but for Illusion (pattern) spells, with its Awesome Display power.
Are there any archetypes, feats, spells, or abilities that raise the HD cap of these spells and what source are they from?