The lady who lives in the apartment over the McCanns' apartment in Portugal...she reported hearing Madeleine screaming for her father for 90 minutes the night before she went missing.
Did Mrs Fenn say whether the parents, Kate and Gerry, were in the apartment with Maddie and the other children during that 90 minutes?
Or were they out drinking and dining that night, too?
Daddy may have gone ahead to meet their friends while Kate stayed back to put the kids to bed. When Maddie didn't want them to go or to be left alone, and she began "protesting", Kate may have shook her, slapped her, yelled at her.... which in turn made Maddie cry out for Daddy.
Kate may have felt her kids were jeopardizing and putting a damper on her fun, spending time with the other adults. So, the next night, to keep from going through another one of Maddie's "tantrums" (and making a scene in front of Mrs Fenn), and having to wait until Maddie fell asleep, she gave her something to sleep.
She may have given Maddie something to sleep the previous night, too... and it may have had a reverse effect (from being wound up, emotional, fearful, etc). Not taking any effect at all. So, did Kate doubled the dose (over dose)the next night?