A mother broke down after telling a jury she found her six-week-old baby boy "out of it" after her first night out since giving birth.
The 29-year-old, who cannot legally be named, said she woke up to find her son "lethargic" and with a swollen lip.
The woman left her son in the care of Raymond McPhee, 23, when she went for a night out in Aberdeen in August 2008.
An alleged assault is said to have left the baby with permanent injuries. Mr McPhee denies attempted murder.
The young mother, who now lives in Ireland, was giving evidence at the High Court in Livingston on the first day of Mr McPhee's trial.
She told the jury the baby had no health issues when he was born in June, 2008 and that she left him with Mr McPhee when she went on her first night out in August.
The mother said Mr McPhee had texted while she was out, saying the baby was "driving him mad".
She said he texted her again just after 2200 BST, saying: "I was sleeping when I heard a thud and he fell of [sic] the bed. Lol (laugh out loud). He is okay though. Might have a fat lip."
The mother said she was worried but felt reassured by Mr McPhee.
When she woke up in the morning however, she said the baby would not take his bottle.
The mother explained: "He was out of it. Lethargic.
"He seemed very sleepy and had a swollen lip. He was quite floppy.
"He was moaning. It wasn't a sound I had heard before. He was unresponsive too."
She took the baby to Aberdeen's Children's Hospital, where he had a seizure.
When she told Mr McPhee, he texted her saying: "I shouldn't have fallen asleep with him on me."
Alison Di Rollo, prosecuting, asked the mother to identify pictures taken in hospital.
The mother confirmed there were injuries on the abdomen and forearm that were not there the night before - and that the boy's eyes had swollen up.
Mr McPhee is alleged to have pinched the baby repeatedly on the head and body, struck him on the head, face and body, forced something into his mouth, squeezed the child and shook him, as well as restricting his breathing with a pillow, or by other means.
The alleged assault is said to have endangered the baby's life and left him severely injured, permanently disfigured, and permanently impaired.
McPhee further denies a second charge, of failing to get the baby medical attention.
The trial, before Lord Uist, continues.