In his “Really?” column in the New York Times, Anahad O’Connor brings up recent research which suggests that drinking 8 glasses of water every day can be beneficial, especially for your kidneys. The authors found that those who had the highest urine volume had lower rates of kidney disease.
On the other hand, another recent study showed that renal hyper-filtration can significantly increase your chances of stroke. They also noted that kidneys tend to overwork in people with the metabolic syndrome, and type 2 diabetes. Notice how obstructive sleep apnea by itself has been linked to increased risk of hypertension, obesity, high cholesterol, and insulin resistance (the metabolic syndrome, or Syndrome X)). In fact, Syndrome Z describes metabolic syndrome plus obstructive sleep apnea.
Knowing that untreated obstructive sleep apnea can also increase urine production by increased levels of atrial naturietic peptide/hormone, it’s not surprising that increased urine production can be linked to higher rates of stroke. Many people who go to the bathroom often at night are found to have untreated obstructive sleep apnea (which increases your risk of stroke). It’s actually been shown that people wake up due to breathing pauses, and not from too much urine production. But the overall levels of urine to go up significantly.
I think that you have to use common sense when it comes to recommending certain volumes for water intake. People have different metabolic needs, and there’s additional water in the normal food that you eat throughout the day. Drinking too much water before bedtime can also increase urine production, leading to more frequent awakenings and poor sleep quality.