Estrogen Deficiency Hampers the Beneficial Effect of Continuous Positive Airway Pressure Therapy on Serum Vitamin D Concentrations in Postmenopausal Women Affected by Obstructive Sleep Apnea

Sleep Performance and Chronotype Behavior in Unilateral Vestibular Hypofunction

OBJECTIVE

To evaluate sleep behavior and its relation to otoneurological parameters in a group of patients with chronic unilateral vestibular hypofunction (UVH) without self-reported sleep disturbances when compared with healthy subjects serving as a control group (CG).

METHODS

Fifty-one patients affected by UVH underwent a retrospective clinical and instrumental otoneurological examination, a 1-week actigraphy sleep analysis, and a series of self-report and performance measures (SRM/PM). A CG of 60 gender- and age-matched healthy subjects was also enrolled. A between-group analysis of variance was performed for each variable, while correlation analysis was performed in UVH patients between otoneurological, SRM/PM, and actigraphy measure scores.

RESULTS

When compared with CG subjects, UVH patients were found to be spending less time sleeping and taking more time to go from being fully awake to asleep, based on actigraphy-based sleep analysis. Also, SRM/PM depicted UVH patients to have poor sleep quality and to be more prone to an evening-type behavior. Correlations were found between vestibular-related functionality indexes and subjective sleep quality, as well as between longer disease duration and reduced sleep time.

CONCLUSION

For the first time, a multiparametric sleep analysis was performed on a large population-based sample of chronic UVH patients. While a different pattern in sleep behavior was found, the cause is still unclear. Further research is needed to expand the extent of knowledge about sleep disruption in vestibular disorders.

LEVEL OF EVIDENCE

Level 3 Laryngoscope, 2021.

25-hydroxyvitamin D levels in patients with obstructive sleep apnea and continuous positive airway pressure treatment: a brief review

The aim of the present study is to summarize the information available, to time, regarding the relationship between obstructive sleep apnea (OSA) and vitamin-D (vD) levels. Moreover, the association between vD deficiency and OSA severity will also be examined. At the end of the present study the possible advantageous effect of CPAP on vD-levels will be summarized. Extensive literature search was conducted in PubMed, Scopus, The Cochrane Library and Embase database. 13 articles were found concerning OSA and vD, of which 2 articles included treatment with a CPAP. Patients with OSA exhibit low levels of vD in the blood serum, and women present an even lower mean value than men. Lack of VD in blood serum seems to be related to the severity of the OSA syndrome, and to the short duration of sleep. OSA patients with concurrent metabolic syndrome exhibit lower serum vD-levels, as compared with those without metabolic syndrome. Long-term continuous positive airway pressure treatment (CPAP) treatment can increase vD-levels in male OSA patients while no change is observed in women. OSA patients demonstrate lower levels of vD in multiple studies. The severity of the OSA may be associated with vD-levels and deficiency, however more studies are needed to assess that relationship due to contradictions in current bibliography. CPAP can increase vD-levels in male patients. The relation between vD and OSA and/or CPAP is important but recent; therefore further research is needed about the exact relationship to be clarified. Also, the effect of gender hormones on vD regulation in OSA patients should be further investigated.

Beneficial effects of estrogens in obstructive sleep apnea hypopnea syndrome

Epidemiological studies showing the higher frequency of obstructive sleep apnea hypopnea syndrome in men, polycystic ovary syndrome (PCOS), and in post-menopausal women suggest the beneficial role of estrogen. These findings are well supported by the pre-clinical studies (ten research studies described in this review) showing that estrogen and phytoestrogens attenuate the deleterious effects of chronic intermittent hypoxia (obstructive apnea in animals) on the genioglossal muscles and on other organs (co-morbidities) in ovariectomized rodents. Moreover, clinical studies (four research studies described in this review) have also shown the beneficial role of estrogen therapy on the parameters of obstructive apnea in post-menopausal women. The beneficial effects of estrogen and phytoestrogens on obstructive sleep apnea and its co morbidities have been attributed to increase in thioredoxin, Nrf-2, activation of p38 MAP kinases, inhibition of vagal C fibers, and attenuation of HIF-1α. It is possible that estrogen-mediated activation of p38 MAP kinase may inhibit HIF-1α to attenuate lung inflammation, which may inhibit the activation of vagal C fibers to attenuate bronchoconstriction and prevent obstruction during sleep. Moreover, estrogen-mediated increase in thioredoxin and Nrf-2 may also contribute in increasing antioxidant defense and attenuating inflammation.

Sleep-Disordered Breathing in Hospitalized Geriatric Patients with Mild Dementia and Its Association with Cognition, Emotion and Mobility

Sleep-disordered breathing (SDB) is an emerging dementia risk factor. Data on the prevalence of SDB in dementia patients and its association with cognitive impairment is so far only based on patients with severe dementia. In 101 geriatric patients mostly with mild dementia recruited on German geriatric wards, SDB was assessed during overnight polygraphy in the patient room with a portable sleep apnea examination device and associations of SDB severity with severity of impairment in cognitive and emotional function as well as mobility were investigated. We also elucidated which factors influence compliance of SDB diagnostics. In 82 of the 101 dementia patients (81.2%), SDB could be assessed. Of those, only 12.2% had an apnea-hypopnea index (AHI) < 5/h demonstrating the absence of SDB. 40.2% exhibited 5/h ≤ AHI < 15/h representing mild SDB, and 47.6% revealed an AHI ≥ 15/h representing moderate/severe SDB. Patients in these three AHI categories did not significant differ from each other in demographical and clinical characteristics. Patients with an AHI ≥ 15/h particularly often presented with heart failure and vitamin D deficiency. We observed a low to moderate association between severity of SDB and severity of dementia. Tolerance of the nasal airflow sensor of at least 6 h was present in less than one third of all patients. The tolerant group exhibited more symptoms of depression and higher physical fitness compared to the non-tolerant group. We observed a high prevalence of SDB also in geriatric patients with mild dementia underlining the importance of SDB screening in the elderly.

The role of vitamin D in obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a common disorder of multifactorial pathogenesis and is associated with obesity, diabetes and cardiovascular disease. Vitamin D is a fat-soluble vitamin with an important function in calcium absorption and homeostasis, which is also implicated in several nonskeletal conditions. The prevalence of vitamin D deficiency is increasing worldwide and is associated with similar metabolic disturbances to OSAS. Moreover, recent data suggest that in OSAS patients serum levels of vitamin D are lower compared with non-apnoeic subjects. However, the mechanisms linking vitamin D deficiency and OSAS are not completely understood and several hypotheses have been advanced. To date, a limited number of studies have assessed the association between lower serum concentrations of vitamin D and OSAS, and have reported inconsistent results. Similarly, contradictory results have been produced by studies which evaluated the effect of continuous positive airway pressure treatment on serum vitamin D levels. The aim of this review is to summarise current knowledge on the association between OSAS and vitamin D levels.

Due to multiple confounding factors, vitamin D deficiency is common among sleep apnoea patients; thus, screening should be performed when clinically indicatedhttp://ow.ly/L3ow30krmol

Changes of vitamin D levels and bone turnover markers after CPAP therapy: a randomized sham-controlled trial

The aim was to investigate whether continuous positive airway pressure treatment could modulate serum vitamin D (25-hydroxyvitamin D) and bone turnover markers (collagen-type 1 cross-linked C-telopeptide, osteocalcin and N-terminal propeptide of type 1 collagen) in secondary analysis from a randomized controlled trial. Sixty-five continuous positive airway pressure-naïve male patients with obstructive sleep apnea (age = 49 ± 12 years, apnea-hypopnea index = 39.9 ± 17.7 events h^-1 , body mass index = 31.3 ± 5.2 kg m^-2 ) were randomized to receive either real (n = 34) or sham (n = 31) continuous positive airway pressure for 12 weeks. At 12 weeks, all participants received real continuous positive airway pressure for an additional 12 weeks. After 12 weeks of continuous positive airway pressure (real versus sham), there were no between-group differences for any of the main outcomes [Δ25-hydroxyvitamin D: -0.80 ± 5.28 ng mL^-1 (mean ± SE) versus 3.08 ± 3.66 ng mL^-1 , P = 0.42; Δcollagen-type 1 cross-linked C-telopeptide: 0.011 ± 0.014 ng mL^-1 versus -0.004 ± 0.009 ng mL^-1 , P = 0.48; Δosteocalcin: 1.13 ± 1.12 ng mL^-1 versus 0.46 ± 0.75 ng mL^-1 , P = 0.80; ΔN-terminal propeptide of type 1 collagen: 2.07 ± 3.05 μg L^-1 versus -1.05 ± 2.13 μg L^-1 , P = 0.48]. There were no further differences in subgroup analyses (continuous positive airway pressure-compliant patients, patients with severe obstructive sleep apnea or sleepy patients). However, after 24 weeks irrespective of initial randomization, vitamin D increased in patients with severe obstructive sleep apnea (9.56 ± 5.51 ng mL^-1 , P = 0.045) and in sleepy patients (14.0 ± 4.69 ng mL^-1 , P = 0.007). Also, there was a significant increase in osteocalcin at 24 weeks (3.27 ± 1.06 ng mL^-1 , P = 0.01) in compliant patients. We conclude that 12 weeks of continuous positive airway pressure did not modulate vitamin D or modulate any of the bone turnover markers compared with sham. However, it is plausible that continuous positive airway pressure may have late beneficial effects on vitamin D levels and bone turnover markers in selected groups of patients with obstructive sleep apnea.

The interfaces between vitamin D, sleep and pain

The role of vitamin D in osteomineral metabolism is well known. Several studies have suggested its action on different biological mechanisms, such as nociceptive sensitivity and sleep-wake cycle modulation. Sleep is an important biological process regulated by different regions of the central nervous system, mainly the hypothalamus, in combination with several neurotransmitters. Pain, which can be classified as nociceptive, neuropathic and psychological, is regulated by both the central and peripheral nervous systems. In the peripheral nervous system, the immune system participates in the inflammatory process that contributes to hyperalgesia. Sleep deprivation is an important condition related to hyperalgesia, and recently it has also been associated with vitamin D. Poor sleep efficiency and sleep disorders have been shown to have an important role in hyperalgesia, and be associated with different vitamin D values. Vitamin D has been inversely correlated with painful manifestations, such as fibromyalgia and rheumatic diseases. Studies have demonstrated a possible action of vitamin D in the regulatory mechanisms of both sleep and pain. The supplementation of vitamin D associated with good sleep hygiene may have a therapeutic role, not only in sleep disorders but also in the prevention and treatment of chronic pain conditions.

Serum Vitamin D Is Significantly Inversely Associated with Disease Severity in Caucasian Adults with Obstructive Sleep Apnea Syndrome

STUDY OBJECTIVES

To evaluate vitamin D (25(OH)D) levels in obstructive sleep apnea syndrome (OSAS) and possible relationships to OSAS severity, sleepiness, lung function, nocturnal heart rate (HR), and body composition. We also aimed to compare the 25(OH)D status of a subset of OSAS patients compared to controls matched for important determinants of both OSAS and vitamin D deficiency (VDD).

METHODS

This was a cross-sectional study conducted at an urban, clinical sleep medicine outpatient center. We recruited newly diagnosed, Caucasian adults who had recently undergone nocturnal polysomnography. We compared body mass index (BMI), body composition (bioelectrical impedance analysis), neck circumference, sleepiness (Epworth Sleepiness Scale), lung function, and vitamin D status (serum 25-hydrpoxyvitamin D (25(OH)D) across OSAS severity categories and non-OSAS subjects. Next, using a case-control design, we compared measures of serum 25(OH)D from OSAS cases to non-OSAS controls who were matched for age, gender, skin pigmentation, sleepiness, season, and BMI.

RESULTS

106 adults (77 male; median age = 54.5; median BMI = 34.3 kg/m(2)) resident in Dublin, Ireland (latitude 53°N) were recruited and categorized as non-OSAS or mild/moderate/severe OSAS. 98% of OSAS cases had insufficient 25(OH)D (< 75 nmol/L), including 72% with VDD (< 50 nmol/L). 25(OH)D levels decreased with OSAS severity (P = 0.003). 25(OH)D was inversely correlated with BMI, percent body fat, AHI, and nocturnal HR. Subsequent multivariate regression analysis revealed that 25(OH)D was independently associated with both AHI (P = 0.016) and nocturnal HR (P = 0.0419). Our separate case-control study revealed that 25(OH)D was significantly lower in OSAS cases than matched, non-OSAS subjects (P = 0.001).

CONCLUSIONS

We observed widespread vitamin D deficiency and insufficiency in a Caucasian, OSAS population. There were significant, independent, inverse relationships between 25(OH)D and AHI as well as nocturnal HR, a known cardiovascular risk factor. Further, 25(OH)D was significantly lower in OSAS cases compared to matched, non-OSAS subjects. We provide evidence that 25(OH)D and OSAS are related, but the role, if any, of replenishment has not been investigated.