Vitamine D en slaap*
Uit twee Amerikaanse studies blijkt dat goede bloedwaarden vitamine D belangrijk zijn in het tegengaan van
slaapproblemen, ook overdag zoals narcolepsie. (Kenmerk van narcolepsie is een overmatige behoefte om gedurende de dag te slapen, zelfs na voldoende nachtrust.) Uit de eerste studie onder 81 deelnemers blijkt dat
bloedwaarden vitamine D omgekeerd evenredig waren met slaapproblemen. Dus hoe hoger de bloedwaarden hoe minder problemen, alhoewel dit alleen voor het merendeel van de deelnemers gold, zij met een blanke huid. Voor zij met een zwarte huid gold deze relatie niet. De tweede studie onder 153
patiënten uit een slaapkliniek, veelal met narcolepsie en spierzwakte, had ruim 80% van de deelnemers te lage bloedwaarden vitamine D. Bij
aanvulling met vitamine D bleek bij de meeste deelnemers de slaapproblemen voorbij te zijn.
Always sleepy? Check your vitamin D levels
Low levels of vitamin D may be to blame for some cases of chronic sleepiness, according to a pair of recent studies by researchers from Louisiana State
University.
In the first study, published in the Journal of Clinical Sleep Medicine, researchers measured vitamin D and sleepiness levels in 81 patients at a sleep clinic. All participants had complained of both trouble sleeping and of "nonspecific pain." They were all eventually diagnosed with some sleep disorder, the most common being obstructive sleep
apnea.
The researchers found that for most participants, sleepiness increased as blood levels of vitamin D decreased. The opposite effect was seen in African-American participants, however, with sleepiness increasing along with levels of vitamin D.
"While we found a significant correlation between vitamin D and sleepiness, the relationship appears to be more complex than we had originally thought," lead researcher David E. McCarty said. "It's important to now do a follow-up study and look deeper into this correlation."
Supplementation cures sleepiness
Vitamin D, Race, and Excessive Daytime Sleepiness
http://dx.doi.org/10.5664/jcsm.2266
David E. McCarty, M.D.1; Aronkumar Reddy, M.D.1; Quinton Keigley, B.S.2; Paul Y. Kim,
Ph.D.1; Andrew A. Marino, Ph.D.1
1Division of Sleep Medicine, Department of Neurology, Louisiana State University Health Sciences Center,
Shreveport, LA; 2School of Medicine, Louisiana State University, Shreveport, LA
Study Objectives
First, to determine whether serum vitamin D levels were correlated with excessive daytime sleepiness
(EDS) in patients with or without vitamin D deficiency (VitDd). Second, to assess whether race affected the relation between vitamin D levels and
EDS.
Methods
Serum 25-hydroxyvitamin D (25OHD) was measured by immunoassay in a consecutive series of 81 sleep clinic patients who complained of sleep problems and nonspecific pain (25OHD < 20
ng/mL ' VitDd). Sleepiness was determined using the Epworth Sleepiness Scale score
([ESSs] ESSs ≥ 10 ' EDS). Correlations were assessed using Pearson r.
Results
In patients without VitDd (25OHD ≥ 20 ng/mL), ESSs was inversely correlated with vitamin D concentration (r = 0.45, p < 0.05). The group consisted of 6% black
patients, compared with 35% for the entire cohort. Among the patients who had VitDd (25OHD < 20
ng/mL), ESSs was directly correlated with 25OHD in black (r = 0.48, p < 0.05) but not white
patients. In black patients, mean ESSs in patients with VitDd were higher and 25OHD levels were lower p < 0.05).
Conclusions
The results suggested the novel possibility that VitDd-related disease has a yet-to-be-identified mechanistic role in the presentation of
sleepiness, sleep disorders, or both. Further research is needed to clarify the
mechanism(s) involved in producing the complex relationships noted.
In a second study, due to be presented at the 25th annual meeting of the Associated Professional Sleep Societies in June, McCarty examined data on 153 sleep clinic patients who were enrolled in a study on sleep disturbances and had complained of chronic pain. The researchers found that 54 percent of the participants were vitamin D deficient, while another 30 percent had blood levels of the vitamin that were classified as insufficient but not yet
deficient.
The findings were not surprising, because prior research had shown that low levels of vitamin D deficiency are often associated with a diffuse form of musculoskeletal pain, called osteomalacic myopathy, that can interfere with sleep.
Because osteomalacic myopathy is known to respond well to treatment with vitamin D supplements, the researchers prescribed supplements to study participants. Many of the participants did then experience a complete end to their daytime sleepiness symptoms. This suggests that vitamin D deficiency may actually be directly causing sleepiness, the researchers noted, perhaps due to its role in regulating inflammation in the body.
"More research is needed to define whether vitamin D deficiency mechanistically contributes to excessive daytime sleepiness and to determine if supplementation offers a novel method for alleviating it," McCarty said.
McCarty noted that his research has already led to changes in the ways that he treats patients with sleep
disturbances.
"The way this study has changed my practice patterns comes from the realization that patients who present for complaints of possible sleep disorders are often vitamin D-deficient," he said.
"Therefore, in the patients I see as a sleep medicine specialist, I tend to screen for vitamin D deficiency in patients who complain of nonspecific musculoskeletal pain, and I recommend supplementation for levels below 30
ng/mL."
He suggests that other clinicians adopt similar practices, pending further research. (Januari 2013)
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