Comments

to those who are saying that physical activity will also result in the same symptoms that they monitored in this study, sorry but no. being physically active will raise your heart rate, but will actually lower stress levels and it won't make a drastic change in your heart rate variability; and, it will also result in deeper more relaxing sleep, on a more consistent basis (why do you think people who are in shape generally sleep better than couch potatoes). also, they aren't talking about your average heart rate, but the amount that your average heart rate fluctuates; having on average a higher or lower heart rate is not anywhere near as bad as having your heart rate fluctuate between 70 bpm and 140 bpm on a consistent basis. granted this is a small and very short-lived study, but I would bet that a long-term study with a larger study group would show the same results.

ideally there should be a natural, or at least more practical sounding, solution, as some of you have said. but if you think about it more practicaly, this a very sensible and cunning solution to a potentialy dangerous, or at least very costly, problem in a city with an already outrageous budget at a time when our economy isn't very good. why retrofit the system? why not use cheap, recylable plastic balls when you're just going to switch to a new resevoir in a few years anyway? seems like a great idea to me.