The incident occurred in an eastern China city where the woman has been detained after her teenaged son was found dead.
The boy was found lying in bed breathless when police arrived at their home in Jinhua City of Zhejiang Province yesterday, Shanghai Daily reported today.
The woman surnamed Jiang sat quietly in the next room and admitted the killing to the police, the report said.
Initial investigation found Jiang strangled her son in the morning because he had refused to get up for breakfast.
Jiang's neighbours described her as being very strict with the boy.