Many Americans report difficulties with sleep. Do any of these sound familiar?
- Regularly getting less than 7-8 hours of sleep per night
- Waking up in the morning not feeling fully well rested most mornings
- Regularly have trouble falling asleep
- Wake up frequently once or more during the night and can’t fall back asleep
- Wake up earlier than intended regularly
- Snore or told you have sleep apnea
- Suffer from daytime sleepiness
If these resonate with you, your sleep quality may be negatively impacting your kidney health. Research has uncovered a strong connection between sleep for general well-being as well as an important key for kidney health.
The Scale of the Problem
Sleep disorders are very common in patient with chronic kidney disease (CKD). Because sleep symptoms can be subjective, it’s difficult to nail down the exact prevalence. Studies report that the prevalence of sleep disorders in kidney patients ranges between 31-57% depending on published studies. Although it appears that there is no association between the severity of sleep disorders and the stage of kidney disease, those who have kidney failure and are on dialysis are more likely to have problem with sleep than other CKD patients.
When you look at specific sleep disorders such as obstructive sleep apnea (OSA) or restless leg syndrome (RLS) you will find that these are very common in patients with CKD. In fact, studies that measured the frequency of sleep apnea in CKD patients reported results as high as 94%.
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Why Adequate Sleep is Important
Insomnia is the most common recognized sleep disorder. It is defined as the subjective complaint of difficulty in initiating or maintaining sleep for at least three times per week for a duration of four weeks or more to a degree that daytime functioning is impaired.
Sleep problems can lead to a decreased performance at work or school. They may slow reaction time increasing the risk for motor vehicle accidents. They have also been linked to depression, anxiety and substance abuse. Sleep disorders have been associated with increased risk for diabetes, high blood pressure and heart disease.
When thinking about sleep health, it is important to think about these following qualities:
- Sleep duration (the total amount of sleep in 24 hours)
- Sleep continuity or efficiency (the ease of falling asleep, staying asleep, and returning to sleep if woken during the night)
- Timing (What time are you sleeping)
- Alertness/sleepiness (the ability to maintain attentive wakefulness throughout the day)
- Satisfaction/quality (the subjective feeling of “good” or “poor” sleep)
A sleep questionnaire can be very helpful in identifying those who have sleep issues and need for intervention. Try our sleep questionnaire here if you’d like to understand your sleep quality better.
Disrupters of Sleep
Many factors can lead to sleep disruption. These factors include toxin exposure, genetic risk, nutritional deficiencies, medications, and of course stress and anxiety.
Toxins
The hours we are sleeping are very important for nerve cells restoration and clean-up. In fact, studies have demonstrated that sleep promotes clearance of neurotoxic waste products that accumulate during waking hours.
The sleep-wake cycle is also important in liver detoxification of toxins and medications. But most importantly, toxins such as arsenic, pesticides, phthalates, polyfluoroalkyl compounds (PFAs) have been specifically linked to sleep troubles in one of the largest studies conducted in the US. Higher levels of urinary arsenic were found to be associated with leg jerks. Pesticides were associated with increased leg cramps during sleep. PFAs not only can directly cause kidney damage, they also disrupt sleep due to increased leg jerks during the night.
Nutrient Deficiencies
There are several nutrients hat are implicated in disrupting sleep:
- Vitamin D , a hormone that interacts with many cellular receptors including those in the gut, bone, breast, prostate, brain, skeletal muscle and the immune system has been found to play an important role in the time to fall asleep.
- Maintaining good blood sugar balance by reducing excessive carbohydrates, and eating foods rich in fiber, healthy fats, and protein is also important for getting good quality sleep.
- Deficiencies of tryptophan, an amino acid precursor of serotonin and melatonin, or B6 which is needed to regulate sleep hormones may also impact sleep.
- Many micronutrient deficiencies have been associated with sleep disturbances, with the strongest link is found between magnesium and zinc deficiency.
Medications and alcohol
Many prescription drugs have been found to interfere with sleep. Medications such as antidepressants, asthma and blood pressure medications are the most common offenders. In addition, many over-the-counter medications such as pain medications, allergy, and cold medication and weight-loss products can contain caffeine or other stimulants that can disrupt sleep.
Even sleep medications, which are commonly used to treat insomnia may cause sleep disturbances. This is because they do not allow those who take them to fall into the normal, deep sleep pattern that results in restorative sleep. Alcohol may make you sleepy, however studies show that regular consumption of alcohol is also disruptive to healthy sleep.
Biological factors
As you may expect, stress has been documented to lead to poor sleep quality. This association is maybe mediated by the hormones that drive up activity of the hypothalamus-pituitary-adrenal (HPA) Axis, driving the fight-or-flight-response. Multiple hormones have been found to affects the sleep cycle, particularly cortisol for example. Cortisol is a driver of inflammation and can contribute to insulin resistance which leads to blood sugar imbalances, which we’ve already learned affect sleep quality.
Lastly, it appears that our genes play an important factor in setting our internal clock. Genes our sleep-wake patterns that can influence our physiology, our cyrcadan rhythm, we utilize nutrients, and handle toxins and medication – all the factors that impact sleep. The field of chronotherapeutics which studies these associations is still in its infancy but we will learn more about it in the near future.
Impact of Poor Sleep on Kidney Health
Poor sleep can impact the kidneys in two ways: directly and indirectly.
Indirectly, the factors we described above may lead to insufficient sleep, poor quality of sleep and apnea can lead to elevated blood pressure (hypertension) or make it more difficult to control. There is also a strong body of evidence linking blood sugar (glucose) metabolism with sleep quality and quantity. Fragmented sleep has been associated with increased insulin resistance and metabolic disease. Finally, fragmented sleep has been shown to impact the hormonal control of satiety and hunger leading to excessive eating and obesity. It is well established that diabetes, hypertension and obesity are associated with linked to the development and progression of CKD.
Directly, sleep can be a key regulator of kidney function. During sleep, sympathetic activity (fight-or-flight) decreases, and parasympathetic activity increases leading to a drop in blood pressure providing a positive benefit on the circulation in the kidneys. Patients with sleep disorders, especially those with sleep apnea may lose this drop in blood pressure because their parasympathetic system doesn’t kick on.
Shift work and irregular sleep timing and poor quality has also been found to affect the regulation of the renin-angiotensin-aldosterone system (RAAS). RAAS plays an important role in the development and progression of kidney disease. Last but not least, obstructive sleep apnea is associated with increased inflammation and oxidative stress which leads to kidney damage.
Impact of Kidney Disease on Sleep
CKD itself can be a risk factor for sleep disorders. Melatonin, which is a hormone secreted by the pineal gland, is responsible for the sleep-wake cycle usually increase during the night to induce sleep. In kidney patients, this natural rhythm seems to be blunted. CKD can lead to a short, fragmented sleep and difficulty falling asleep. In addition, CKD has been associated with OSA, restless leg syndrome (RLS), and increased leg cramps.
The Bottom Line
Sleep disorders are common in kidney disease and they have been associated with the development and progression of CKD. They also can lead to inflammation, diabetes, hypertension and obesity. Multiple factors plan a role in the development of sleep disorders. It is important to work with an Integrative or Functional medicine provider to evaluate your sleep and kidney health.
