The researchers found more breathing pauses, more night-time awakenings, less rapid eye movement (REM) sleep and lower blood-oxygen levels among patients with hypertension.
The study examined 133 adults referred for suspected obstructive sleep apnea (OSA), a disorder in which the airway repeatedly collapses during sleep.
Of these, 52 had diagnosed arterial hypertension and 81 had normal blood pressure.
All participants underwent full-night polysomnography, the comprehensive “gold-standard” test that records brain waves, eye movements, muscle tone, breathing, heart activity and limb movements to map sleep stages and disruptions.
The team described this method as the most reliable way to assess sleep quality.
The work, conducted at Wrocław Medical University, in partnership with the Wrocław University of Environmental and Life Sciences in the country's southwest, was published in the journal Dental and Medical Problems.
Compared with normotensive (having normal blood pressure) peers, people with hypertension had a higher apnea–hypopnea index, more arousals related to disordered breathing, more periodic limb movements, lower sleep efficiency and lower minimum oxygen saturation.
They also spent less time in REM sleep, the phase important for processing emotions and consolidating memories, which may help explain reports of headaches and sharper pain perception in this group, the authors said.
The researchers also looked at blood chemistry. Patients with hypertension showed lower magnesium levels and higher concentrations of C-reactive protein, glucose and uric acid.
C-reactive protein, or CRP, is a marker of systemic inflammation often used to gauge cardiovascular risk.
Crucially, greater sleep fragmentation correlated with lower calcium levels, which indirectly points to a role for vitamin D in night-time awakenings, because vitamin D helps regulate calcium balance.
While vitamin D levels did not differ significantly when all participants had sleep disorders, hypertensive patients with sleep problems had markedly lower vitamin D than healthy sleepers without such problems, the team reported.
"We saw that patients with hypertension not only more often had obstructive sleep apnea, it was more severe," said study lead, Prof. Helena Martynowicz of Wrocław Medical University.
She added that reduced REM sleep in this group could impair memory consolidation and emotional regulation, and that frequent awakenings and interrupted sleep add strain to the heart and blood vessels.
REM sleep is the dream-rich stage linked to memory and mood.
Although the study focused on patients already referred for suspected OSA, its findings align with wider research connecting sleep apnea and disturbed sleep with elevated cardiovascular risk.
Repeated overnight drops in oxygen and surges in stress hormones can drive sympathetic nervous-system activation, which in turn supports the development of hypertension and heart disease.
The authors say their results support using high-quality sleep assessment, including polysomnography where appropriate, as an additional indicator when evaluating cardiovascular and metabolic risk in people with hypertension.
Shorter REM duration, fragmented sleep, reduced efficiency and frequent awakenings could be red flags worth discussing with a clinician, particularly when combined with daytime symptoms such as sleepiness or morning headaches.
As with any observational study, the results show associations rather than causation and are limited to a clinical sample.
Still, they underscore a practical point for patients and doctors alike: how you sleep may be telling your heart something important—and, in turn, telling you something important about your heart.
(rt/gs)
Source: PAP, poradnikzdrowie.pl