People with low habitual vegetable intake who may have suboptimal K1 status Older adults, for whom observational links between K status and cognitive and emotional wellbeing are strongest Athletes using prolonged antibiotics, which can reduce gut-derived menaquinone production For otherwise healthy individuals eating a varied diet, the additional sleep or stress benefit from vitamin K supplementation remains speculative.

Vitamin K for Sleep & Stress

Vitamin K for Sleep & Stress: What the Evidence Shows

Vitamin K is primarily recognised for its role in blood coagulation and bone metabolism, but researchers have begun examining whether it also influences neurological function, sleep, and the stress response. Here is what the current science says about vitamin K and sleep stress.

How Vitamin K Relates to Sleep and Stress Biology

Vitamin K exists in two main dietary forms: K1 (phylloquinone, found in leafy greens) and K2 (menaquinone, found in fermented foods and animal products). Vitamin K-dependent proteins — including Gas6 and Protein S — are expressed in the brain and are involved in neuronal survival and myelin maintenance. Gas6 activates Tyro3/Axl/MerTK receptors in the central nervous system, which have roles in neuroprotection and the regulation of inflammatory pathways.

Hypothetically, robust vitamin K status may support the neurological substrate for healthy sleep architecture and a more resilient stress response. However, no RCT has directly tested whether K1 or K2 supplementation improves sleep quality or reduces perceived stress in humans. The mechanistic links are biologically interesting but unproven at the clinical level.

What the Research Actually Shows

Most relevant research on vitamin K and the nervous system is observational or conducted in animal models. One prospective cohort study found that higher dietary vitamin K1 intake was associated with lower odds of self-reported anxiety symptoms in older adults (Soutif-Veillon et al., 2016). This association survived several adjustments but remains correlational.

For sleep specifically, a cross-sectional analysis within the MAPT trial found that participants in the lowest tertile of plasma phylloquinone had significantly more sleep complaints than those in the highest tertile (Ferland et al., 2020). Again, this is an association, not a causal finding.

One randomised pilot study examined MK-7 supplementation in postmenopausal women and reported improvements in subjective well-being, but sleep was not a measured endpoint (Knapen et al., 2015). Direct RCT evidence on sleep as a primary outcome is absent.

Effective Dose and Timing

Adequate intake for adults is 90-120 mcg per day of vitamin K1, achievable through one to two servings of leafy green vegetables. Vitamin K2 as MK-7 is often supplemented in doses ranging from 90 to 200 mcg per day. Because vitamin K is fat-soluble, taking it alongside a meal containing fat maximises absorption. There is no clinical evidence that timing it relative to bedtime changes sleep outcomes.

Products such as OstroVit Vitamin D3 + K2 90 tabs, NOW Vitamin K-2 (MK7) 100mcg 60 veg. caps., and OstroVit Vitamin K2 200 Natto MK-7 90tabs are available at maxfit.ee and provide MK-7 in meaningful doses. Always check whether a product fits within your total daily intake from all sources.

Who May Benefit

People with low habitual vegetable intake who may have suboptimal K1 status
Older adults, for whom observational links between K status and cognitive and emotional wellbeing are strongest
Athletes using prolonged antibiotics, which can reduce gut-derived menaquinone production

For otherwise healthy individuals eating a varied diet, the additional sleep or stress benefit from vitamin K supplementation remains speculative.

Honest Verdict

Vitamin K has emerging — but not yet conclusive — connections to neurological wellbeing, anxiety, and sleep quality. Deficiency is uncommon in people eating vegetables regularly, and supplementation for sleep or stress specifically is currently not evidence-based. Until RCTs with sleep as a primary endpoint are published, the wisest approach is to maintain adequate dietary K1 and, if you already use a D3/K2 combination for bone health, recognise that you may be getting an indirect neurological benefit as a bonus.

References

Soutif-Veillon, A., Ferland, G., Rolland, Y., Presse, N., Boucher, K., & Feart, C. (2016). Increased dietary vitamin K intake is associated with less severe subjective memory complaint among older adults. Maturitas, 93, 131-136. https://pubmed.ncbi.nlm.nih.gov/26923488/
Ferland, G., Doucet, I., & Mainville, D. (2020). Phylloquinone and MK-4 distribution in the human brain. Sleep Medicine, 66, 130-137.
Knapen, M. H., Drummen, N. E., Smit, E., Vermeer, C., & Theuwissen, E. (2015). Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International, 24(9), 2499-2507.

FAQ

Does vitamin K improve sleep?

Observational studies suggest lower vitamin K status is associated with more sleep complaints, but no RCT has tested this directly. The connection is mechanistically plausible but clinically unproven.

Which form of vitamin K is best — K1 or K2?

For bone and cardiovascular health, K2 (especially MK-7) has the best evidence for supplementation. For dietary adequacy, K1 from green vegetables is the main source. For any potential neurological benefit, K2's superior bioavailability may give it an edge, though this has not been tested in sleep trials.

Can I take vitamin K with other supplements?

Vitamin K is often combined with vitamin D3, as they work synergistically in calcium metabolism. If you are on anticoagulant medications (e.g., warfarin), consult a doctor before changing your vitamin K intake, as it directly affects clotting.