Sleep learning?

[Piffle]

So I'm running the house where four little old ladies are living with their four grown children.  All the old biddies are sick, so I'm trying to keep them from compulsively cleaning so they don't die or anything.  I tell Prudence to go to bed, and a little window pops up informing me that Verity has gained a point of cooking skill.  Verity is sound asleep in the bed next to Prudence.

Verity maxed her cooking skill some hours later, while playing kicky bag with Charity.

Anyone else experience this?  I'm wondering if it's a NL bug, or some weird side effect to one of my old hacks.

[Ancient Sim]

I've not had messages, but I've seen skill bars hovering over beds several times.  I ve a pic of one little girl earning cooking skill while she was sleeping (she'd been on the Skillinator earlier) and another of someone gaining skill in something (I won't dwell on what) while they were woo-hooing in Lizzlove's waterbed.  It's probably caused by the skilling function not quite cancelling out in time before the next activity starts, or something.