This is also called gastric reflux. In this condition, the acids from the stomach enter into the food pipe (oesophagus) and cause a burning sensation in the chest area. Heartburn is three times more common in people with asthma. If heartburn is frequent, the acids in the food pipe irritate one nerve of the autonomous nervous system called the vagus nerve. Irritation of the vagus nerve causes constriction of the airways and therefore leads to asthmatic symptoms. Heartburn is more common at night when a person is in a reclining posture Stress: Asthma worsens during periods of stress and anxiety. This is because emotional outbursts such as crying, shouting, fear, etc, stimulate the nerves of the airways and tighten them.