Sudden infant death syndrome practice

You are discharging a 5-week-old boy after an admission with bronchiolitis. His mother smokes ten cigarettes a day outdoors. She tells you she is so exhausted that she now feeds him on the lounge at night and they both fall asleep there until morning; she has stopped using his cot because he wakes as soon as she puts him down. She asks what she should change first. Which one of the following pieces of advice would most reduce his risk of dying suddenly?