|MadSci Network: General Biology|
This is a great question. The main reason many individuals feel "tired" after a hot bath, long hot shower, or time in a sauna is that the individual has finally "relaxed" from a hard day or work, play, training, etc. Today, the far most common factor in feeling tired after a hot bath is stress. Stress has become a normal, every day condition in our lives - sometimes we know the stress is there and other times not. And with times as stressful and as busy as they are these days, it is often difficult to find ways to relax. However, there is one "ancient" form of relaxation that has stood the test of time - soaking in warm, relaxing waters. If one thing makes your muscles go limp and release all the tensions they built up all day, it's a good hot bath. But for some, a bath is not their thing. For them, a long hot shower or sauna does the same thing - cause the individual to relax and release the tensions accumulating in their muscles. The primary release mechanism for stress in muscles is the warmth of the water or steam. When the body is under stress, blood vessels constrict which in turn causes your body's muscles to work a little harder and become stiffer. It also causes the muscles to not rid waste products from their cells nor heal itself as quickly as it should. But, the great thing about soaking in warm water is that it causes blood vessels to dilate and get blood into tired muscles. The cells are then able to get rid of waste products and not be stiff. And when your tired muscles finally relax (your muscles worked hard all day under all that stress or physical activity), you yourself finally relax and feel tired. So now when you get out of nice hot bath and feel tired, you know your muscles have worked hard all day, they are tired, and are finally relaxed. And then it's time for some relaxing sleep to give the entire body time to heal and rest before tomorrow's adventures.
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