Ayelet Frisch said medics treated him at his home today night and detected a "light irregular heart rate." She said the doctors decided he should spend the night in hospital for observation.
Peres was discharged from hospital last week after suffering a mild heart attack.
Peres completed his seven-year term as president in 2014. He remains active through his non-governmental Peres Center for Peace, which promotes coexistence between Arabs and Jews. In a seven-decade political career, Peres served three stints as prime minister.