Hi mummies ... my 1 years old baby coughing when he sleeping.. means he catch a cold ? But he never cough when he is awake...

Check his nose. Is it runny or blocked? If so it could be back-drip, mucus from the nose dripping back down the throat when he's sleeping. He may be having a cold or allergies, and should get it treated soonish to avoid a secondary infection like ear infection.