I found a passage about this in Colin's book.
What Bambs’s psychiatrist, Dr Ferguson, did not explain to me at either of our meetings were the usual side effects of these major tranquillisers, also known as neuroleptics, and a neuroleptic-induced brain disease called Tardive Dyskinesia. Which would develop as a result of prolonged use of them.
Bamb’s had been on various combinations, in often high does, for the best part of two years.
It's so sad that Sheila's family didn't know about, and understand, this was what was happening to Sheila and why she appeared as she did to many people...poor girl!
Obviously CC's book is a primary source.
There is no possibilty Sheila could have committed the massacre. Even in the 0.1% chance she did wake up in the middle of the night and decide she wanted to.
She was a recovering anorexic and 7 stone. The pictures show she was almost child like.
She had no experience of weapons and would not know how to chamber, load and put the silencer on or take it off.
She had co ordination problems and sufferred from Tardrive Dyskenisia. She couldn't put sugar in coffee and found it difficult getting up off chairs. The medication would just make her drowsy.