Patients with hypertension sleep worse than those with normal blood pressure. They more often suffer from sleep apnea; their sleep is interrupted, and the REM phase—the phase most connected with emotions and memory—is noticeably shorter. This discovery by Polish scientists from the Medical University and the University of Environmental and Life Sciences in Wrocław shows how strongly the cardiovascular system’s condition is intertwined with sleep quality and the body’s vitamin-mineral balance. 

A Night in the Sleep Laboratory 

The study conducted in Wrocław involved 133 people suspected of obstructive sleep apnea. Each patient underwent polysomnography, the most precise sleep study available in medicine. Brain activity, breathing, heart function, body movements, and blood oxygen levels were recorded. The results clearly showed differences between people with hypertension and those with normal blood pressure. 

Hypertensive patients slept less efficiently, experienced more frequent awakenings, and had lower blood oxygen saturation. This group also exhibited more limb movements, and obstructive sleep apnea was not only more common but also more severe. Interestingly, in people with normal blood pressure, frequent awakenings were often caused by bruxism (teeth grinding), whereas in hypertensive patients, breathing interruptions predominated. 

The Biochemistry of Sleep 

Researchers also analyzed blood samples from the participants. People with hypertension had lower magnesium levels and higher concentrations of C-reactive protein, glucose, and uric acid—all indicators associated with a greater risk of cardiovascular diseases. Differences were also observed in vitamin D levels, but only when comparing hypertensive patients with sleep disorders to healthy individuals without such problems. This particular group—combining both risk factors—had significantly lower vitamin D levels. 

Scientists highlighted an important mechanism: sleep fragmentation correlated with lower blood calcium levels, and vitamin D plays a crucial role in calcium metabolism. Vitamin D deficiency means poorer calcium absorption and dysfunctions in nerves and muscles, including those responsible for controlling breathing during sleep. This may explain why people with low vitamin D and hypertension wake up more often during the night. 

The results from the Wrocław team fit into a growing body of research indicating a link between sleep, vitamin D, and cardiovascular health. Scientific reviews suggest that people with higher vitamin D levels are less likely to suffer from hypertension, although clinical trials on supplementation are inconclusive. It is known, however, that sleep quality directly impacts heart health—interrupted sleep increases the risk of hypertension, metabolic disorders, and cardiovascular disease. 

The REM phase has particular importance. It is precisely during this phase that the brain organizes memories and processes emotions. Studies show that people with more REM sleep are less likely to develop heart failure. Meanwhile, hypertensive patients experience shorter REM phases, potentially increasing heart strain. 

What Does This Mean? 

These scientific findings indicate that assessing sleep quality could become an important element in diagnosing and preventing cardiovascular diseases. Polysomnography, once mainly associated with diagnosing sleep apnea, may provide valuable information about overall health risks. At the same time, research suggests that maintaining adequate vitamin D, calcium, and magnesium levels may support not only bones and immunity but also healthy sleep and cardiovascular function.