BradycardiaBradycardia (also sinus bradycardia) is a slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram. It is considered to be a normal heart rate during sleep, in young and healthy or elderly adults, and in athletes. In some people, bradycardia below 60 BPM may be associated with fatigue, weakness, dizziness, sweating, and fainting. The term "relative bradycardia" is used to refer to a heart rate slower than an individual's typical resting heart rate.
StethoscopeThe stethoscope is a medical device for auscultation, or listening to internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the skin, with either one or two tubes connected to two earpieces. A stethoscope can be used to listen to the sounds made by the heart, lungs or intestines, as well as blood flow in arteries and veins. In combination with a manual sphygmomanometer, it is commonly used when measuring blood pressure.
Sleep and breathingWhen we sleep, our breathing changes due to normal biological processes that affect both our respiratory and muscular systems. Breathing changes as we transition from wakefulness to sleep. These changes arise due to biological changes in the processes that regulate our breathing. When we fall asleep, minute ventilation (the amount of air that we breathe per minute) reduces due to decreased metabolism. During NREM sleep, we move through three sleep stages, with each progressively deeper than the last.
