Sighs

    Just when we think there couldn't possibly be any more mysteries left to solve about the human anatomy, comes another discovery. This one has to do with sighing. It turns out that the involuntary reflex that is generally associated with sadness or despair is crucial to our well-being. That is why researchers at UCLA and Stanford University were determined to find out what triggers the spontaneous action, without which our lungs would collapse!

    A sigh is just a deep breath which starts out as a normal breath but extends when we inhale more air before letting it out. And while you may not realize it, most of us sigh once about every five minutes, or approximately twelve times an hour, regardless of whether we are sad or depressed.

    To understand sighing we need to learn a little about how the lungs function. Our lungs are comprised of many branches or bronchioles. Each of these divides into millions of tiny sacs called alveoli. The alveolus (singular for alveoli) is where the respiratory system comes in contact with the circulatory system and conducts the all-important exchange of oxygen and carbon dioxide. The sacs inflate and collapse as we breathe in and out. However, the alveoli need to be inflated completely to avoid them from collapsing. Since that cannot be accomplished with just regular breathing, our body takes a deep breath or what we call a 'sigh' every few minutes.

   Though scientists have known this for many years, they had not been able to identify what triggers this involuntary life-sustaining reflex. However, two previous studies had each found half the answer to the puzzle. One study was conducted by UCLA and the other at Stanford University. Now thanks to a collaboration between the two institutions, the mystery has been finally solved. 

   They even began to conduct further studies on sighing. This study was done on mice. They discovered that  peptides triggered the nerve cells that activate the rodent's muscles, which in turn instigate the involuntary sighs. The researchers said that when they blocked one set of peptides the mice sighed at half the rate. When the peptides were blocked completely, the mice stopped sighing altogether. Conversely, when the peptides were increased the number of sighs went up substantially.  The number of sighs increased from from 40 times an hour to 400 times!

   The study which was published in the digital edition of the science journal, Nature, on February 8, opens the possibilities of new medications to help people with severe respiratory conditions. It will also assist in a more efficient design of life support systems. But most important of all, it gives us a compelling reason to sigh! So go ahead and let out a long deep one — It will do your body good!