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COLUMN: Sleep vs hydration — finding the ideal balance

Cutting out liquids before bed can have unexpected consequences
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How many trips do you make to the bathroom each night, and does it really matter? Is the frequency related to our hydration habits, and will drinking water before bed increase or reduce your nightly trip count?

The answers seem pretty much self-evident. As long as we get a total of seven to nine hours sleep each night, we should be okay. Drink less before you go to bed and you’ll sleep with fewer bathroom interruptions. It doesn’t seem like rocket science.

Wrong. How we sleep, and how many interruptions we have during the night, affect everything from blood pressure to cognitive ability — and drinking less before we go to bed may in fact be causing us to wake up more frequently.

If you get up more than once during the night to urinate, you have nocturia. One in three people over 30 have nocturia, and it affects all genders, although frequently for different reasons. As we reach 50 years old, that number rises to 50 percent. Before age 50, nocturia is more common in women, after age 50, men are affected more.

Nocturia has many causes, both lifestyle and health-related.

Consuming too much fluid and the timing of that consumption can result in nocturia. Caffeine and alcohol are strong diuretics, and are best avoided later in the day and evening. Timing and dose are also important for diuretic medications such as water pills, cardiac glycosides, propoxyphene and others.

Health-related conditions that cause nocturia are many, including reduced bladder capacity, enlarged or obstructed prostate, infections, diabetes, high blood pressure, edema (water retention in the legs) and kidney malfunction. If you think you may have any of these or other underlying issues, consult a professional.

Okay, so I know I have an enlarged prostate, and four nightly excursions to the bathroom is my norm. Not to worry. I’m not a medication guy, and I can live with it, or so I thought until I read a study on how and why getting up too frequently to pee effects mental health.

All the intricacies aren’t completely known, yet a 2023 study published in Neurosciences Journal, and vetted by the United States National Center for Biotechnology Information, was confident in stating, “A reduction in sleep does not occur independently of the effects on memory, attention, alertness, judgment, decision-making, and overall cognitive abilities in the brain, resulting in decreased function and impaired cognitive performance.”

That one kinda got my attention — I definitely don’t have a lot of mental faculties to spare.

Were there lifestyle changes I could make that could reduce my nocturnal wanderings?

Reducing coffee and alcohol consumption are at the top of every list, especially late in the day, so they’re pretty much gone for me now.

We lose approximately one litre of water each night through breathing

Harvard Health, a publication of Harvard Medical School, says, “A high blood sugar level causes sugar to spill into urine, dragging lots of water with it,” and, “Calcium from the blood can get into the urine, pulling lots of water along with it.” Sodium makes your kidneys work hard to dissipate the salt quickly, also causing excess urine.

Well that clarifies any mystery as to what my body had been doing each night after my favourite late-night bedtime snack – nice salty peanuts mixed with medium-sweet chocolate chips, washed down with chocolate oat milk. I’ve switched to a single apple now.

The recommendation that is confounding me though is the timing of my hydration. When is the optimal time to drink water to maintain good health while trying to reduce nightly bathroom trips?

The Cleveland Clinic says stop drinking water two hours before you go to bed. The American Urological Association says four hours before bedtime, and Harvard Health says four to five hours.

All the above specialists acknowledge that staying hydrated during the day is important to our health, but see nothing wrong with recommending up to 12 hydration-free hours (four hours before bedtime plus eight hours sleeping) at night. This didn’t make sense, because we know that our whole body works overtime when we sleep. It repairs our muscles, organs and cells, produces additional hormones and chemicals that strengthen our immune systems, and allows our brain to sort through and clean out the day’s trash.

Dr Jessica Vensel Rundo, a neurologist and sleep disorder specialist, somewhat agrees. She writes in a 2022 paper that, “In moderate amounts, drinking water in the evening can still be beneficial. Water is an essential nutrient that keeps your body hydrated, joints lubricated, regulates body temperature, breaks down waste and much more.”

We lose approximately one litre of water each night through breathing, and 70 percent of Canadians are chronically dehydrated. For those folks, having some extra water at night is a benefit.

A 2020 study in Scientific Reports suggests that drinking water before bed may lower blood pressure, reducing the strain on our — our rest, digest and recover state. This in turn helps with falling asleep and staying asleep.

A 2014 study confirmed that water deprivation during nighttime can impact one’s sleep-wake cycle, reducing sleep quality. Increased blood circulation caused by drinking warm water before bedtime will increase sweat output, removing excess toxins and cleaning skin cells.

There are even suggestions that those with nasal congestion should drink before sleeping. We lose more water when we breathe through our mouth than nose, so a stuffed nose may dehydrate us during the night.

There is no consensus on whether reducing water intake before bed is entirely beneficial. Part of the answer is finding balance in what we as unique biological individuals are trying to achieve through hydration or the lack of it, versus any benefits that might be lost.

Who knew a glass of water before bed could be so controversial?


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John Swart

About the Author: John Swart

After three decades co-owning various southern Ontario small businesses with his wife, Els, John Swart has enjoyed 15 years in retirement volunteering, bicycling the world, and feature writing.
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