Re: Why do we feel tired after a hot bath or a sauna ?

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.