Tightness and congestion in the chest when lying down may be caused by pleurisy, intercostal neuralgia and cardiac insufficiency. 1. Pleurisy: this is due to the inflammatory exudate that occurs with pleurisy, which can put pressure on the lung tissue at the lower edge of the chest cavity, leading to chest tightness and shortness of breath when lying down. 2. Intercostal neuralgia: This may cause muscle tension, which can lead to chest tightness and congestion. 3. Cardiac insufficiency: when the patient is lying on his back, the amount of returned blood increases and the heart is overburdened, producing pulmonary stasis and leading to chest tightness and congestion. If the symptoms of chest tightness and congestion are not relieved when lying down, or when accompanied by other symptoms, you should go to the hospital in time, and give targeted treatment after clarifying the cause.