Breathlessness is a symptom that can develop suddenly or gradually and is often present only on exercise. The presence of breathlessness when walking uphill or climbing a set of stairs can be an early sign of a cardiac problem. This problem may be related to the pumping function of the heart or the function of the cardiac valves and is usually called “heart failure”. At later stages of heart failure people may experience breathlessness when lying flat on a bed and therefore use more than one pillow to sleep at night. Others may wake up suddenly in the middle of the night feeling that they cannot breathe and run to the window to get some air. Heart failure may sometimes be related to a “weak” heart and can manifest as profound tiredness.