Written by Chrystal Moulton, Science Writer. Logistical regression analysis showed that individuals with low serum B12 were more likely to experience high sleep latency and were also prone to disturbance in their natural sleep cycle (P<0.05).

Vitamin B12 supports neurotransmitter production, myelin sheath integrity and overall maintenance of nervous system functioning¹. Some studies have also suggested an association between Vitamin B12 and sleep, however, these findings altogether are inconclusive^2-5.

Obstructive Sleep Apnea is a complex disorder signified by partial or complete obstruction of the upper airway during sleep⁶. Individuals with this disorder experience autonomic alterations, chronic intermittent hypoxemia, sleep fragmentation, and hemodynamic disturbances⁷. Furthermore, untreated sleep apnea is associated with increased risk of adverse cardiovascular and metabolic outcomes⁸.

In this study, researchers investigated the effect of serum B12 on sleep parameters and the risk of cardiovascular events in patients diagnosed with obstructive sleep apnea⁶.

This study was designed as a cross-sectional analysis conducted in the Sleep Disorders Center located in Crete (southern region of Greece). Patients aged 18yrs or more with complete serum B12 data, demographic and questionnaire data, and at least 5 events/hour on the apnea-hypopnea index (AHI) during polysomnography were included in this study. Patients with incomplete data, conditions which could impact B12 absorption, other sleep disorders, or taking supplements or medication were excluded from the trial. During polysomnography, researchers analyzed various sleep parameters including:

• Sleep efficiency (SE) – the amount of time spent sleeping while in bed (<85% considered low sleep efficiency).
• Total sleep time (TST) – total time spent sleeping
• Sleep latency – the amount of time it takes to fall asleep
• Wakefulness after sleep onset (WASO) – time spent awake after sleep onset
• Apnea-hypopnea index (AHI) – an American standard index used to rate the severity of obstructive sleep apnea based on symptoms occurring per hour. [Categories: severe (≥30 events/hr), moderate (15-29 events/hr), mild (5-14 events/hr)].

Researchers also analyzed sleep time with oxygen saturation <90% (TST90), oxygen desaturation index (ODI), resting room air pulse oximetry (SpO₂), non-REM/ REM sleep, and arousal index (AI). Fasting blood samples were collected and used to assess serum B12 level. Since no official standard serum value exists for B12, researchers used the median value within this study population to create a low versus normal serum B12 group. The median value of serum B12 in this study population was 380.5 pg/mL. Participants with serum B12 ≥ 380.5 pg/mL were considered normal in this study. Individuals with serum B12 < 380.5 pg/mL were categorized as the low serum B12 group. Sample t-tests were used to measure continuous variables while the chi-square tests were used to measure categorical variables. Logistical regression was used to predict the association between polysomnographic parameters in the low serum B12 group and cardiovascular disease risk.

Of 2105 patients enrolled, 1468 were eligible for participation in this study. Except for age (p= 0.028), no statistically significant differences were observed between patients in the low serum B12 group (<380.5 pg/mL; Age = 54.75 ± 14.57) versus the normal serum B12 group (≥380.5 pg/mL; Age = 53.08 ± 14.33). Researchers observed several polysomnographic parameters which were significantly correlated with low serum B12 (see Table 1).

Table 1. Polysomnographic (PSG) parameters observed in normal vs. low B12 group

Sleep latency is expressed as the median value. Sleep efficiency and REM (%TST) [defined as the % of REM sleep within total sleep time] are expressed as means ± standard deviation.

No significant differences were observed in other parameters of sleep quality (i.e. arousal index (AI), WASO, SWS (%TST)) nor obstructive sleep apnea severity (TST90(%), ODI, AHI, AHI REM, average and lowest SpO₂). Logistical regression analysis showed that individuals in the low serum B12 group were more likely to experience sleep latency (OR = 1.006, p<0.001) and more likely to experience high sleep latency [≥40min] (OR= 1.240, p= 0.045). Patients with low serum B12 were also prone to disturbance in their natural sleep cycle. Low serum vitamin B12 was positively associated with non-REM sleep >80% of total sleep time (NREM >80%TST; OR =2.312, p= 0.038) and REM sleep < 20% of total sleep time (REM<20%; OR = 2.858, p= 0.018). Overall, REM sleep was negatively associated with low serum vitamin B12 (REM (%TST); OR= 0.972, p= 0.049). Researchers also found that low serum B12 (<380.5 pg/mL) [OR= 1.599, p= 0.034] and moderate to severe AHI (≥15 events/hr) [OR = 1.727, p= 0.051] were significantly associated with the risk of cardiovascular disease after adjusting for confounding variables.

Results from this study demonstrated that low serum B12 (<380.5 pg/mL) was significantly associated with long sleep latency, poor sleep quality, disturbance in natural sleep cycle, and the risk of cardiovascular disease. Researchers noted that despite the limitations of the study (i.e. no defined standard for B12, no control group, non-generalizable due to unique population, etc.), these findings warrant further investigation into the effects of serum B12 on sleep quality and the possibility of B12 as an adjunctive therapy in patients with obstructive sleep apnea. Additional studies will be needed to verify these results.

Source: Bouloukaki, Izolde, Antonios Christodoulakis, Theofilos Vouis, Violeta Moniaki, Eleni Mavroudi, Eleftherios Kallergis, Ioanna Tsiligianni, and Sophia E. Schiza. “Association of Vitamin B12 Status with Polysomnographic Parameters and Cardiovascular Disease in Patients with Obstructive Sleep Apnoea.” Nutrients 17, no. 19 (2025): 3079.

© 2025 by the authors

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Posted May 4, 2026.

Chrystal is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Chicago.

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