Urinating before bed can sometimes cause urine reflux, allowing bacteria to flow back into the kidneys, which may lead to pyelonephritis and even chronic kidney failure.

Below are 4 bedtime habits that can harm your kidneys:

1. Staying up late for long periods

Regularly staying up late can disrupt the body’s biological clock, leading to hormonal and metabolic disorders. It overstimulates the sympathetic nervous system, which can cause blood pressure fluctuations and hypertension — both major risk factors for chronic kidney disease.

In addition, staying up late increases the body’s metabolic activity, which leads to greater waste production and toxin accumulation, weakening kidney function over time.

2. Holding in urine before sleep

Holding in urine for extended periods (especially overnight) increases bladder pressure, compressing blood vessels in the bladder wall and causing local ischemia in the bladder mucosa. This condition can easily lead to urinary tract infections.

In severe cases, urine may flow backward, carrying bacteria into the kidneys, resulting in pyelonephritis and even chronic kidney failure.

3. Doing intense exercise before bedtime

Some people enjoy running or working out in the evening, but exercising too vigorously before sleep can stimulate the sympathetic nerves, raise blood pressure, and affect blood flow to the kidneys.

Moreover, strenuous exercise increases the production of metabolic waste such as lactic acid and urea nitrogen, placing additional strain on the kidneys.

Therefore, it’s best to avoid high-intensity workouts before bedtime. Instead, opt for light exercises like yoga, stretching, or walking to help improve sleep quality.

If your urine turns dark brown (tea-colored) after exercising, you should be alert to the possibility of rhabdomyolysis and seek medical attention as soon as possible.

4. Frequently eating late-night snacks

Regularly eating late at night — especially salty or fatty foods — causes the body to retain water and sodium, increasing the metabolic burden on the kidneys.

Additionally, consuming excessive amounts of protein over a long period can also strain the kidneys and gradually impair their function.