Recently, some netizens posted that they always don't sleep enough, even if they sleep 8 hours on weekdays and 12 hours on weekends, they still can't meet their sleep needs.
Image source: Little Red Book
Seeing that someone said that it might be a lack of vitamin D, this netizen went to the hospital for examination. The test results showed that the full test result of ta's 25-hydroxyvitamin D [25(OH)D] was only 5.52 ng/mL. Under normal circumstances, vitamin D in the body should be 25(OH)D ≥20ng/mL.
So, does a lack of vitamin D lead to sleep deprivation?
What does vitamin D do?
Vitamin D is a fat-soluble vitamin whose main role is to promote the absorption of calcium from food in the intestines, which contributes to bone health. In addition, it regulates many other cellular functions in the body.
The Dietary Nutrient Reference Intakes for Chinese Residents recommends that people aged 64 consume 400 international units (IU) of vitamin D per day (400IU is equivalent to 0.1 mg). Usually during a hospital exam, we check the level of 25-hydroxyvitamin D [25(OH)D] in the blood. According to the People's Republic of China Health Industry Standard (WS/T) "Screening Method for Vitamin D Deficiency in the Population", when the blood level of 25(OH)D is greater than 20ng/L, it indicates that the nutritional status of vitamin D is normal, and less than 12ng/L indicates deficiency.
Image source: "Screening methods for vitamin D deficiency in the population"
Lack of vitamin D can lead to osteoporosis, and the screenshot of this netizen commenting on the supplement "usual leg cramps" may also be related to D deficiency.
But can vitamin D deficiency cause sleep problems?
Always "not enough sleep"
Is it due to vitamin D deficiency?
For "people who never sleep enough", their sleep is likely to be in a "non-restorative sleep" state.
In 1987, the American Psychiatric Association first listed "non-restorative sleep" as a symptom of insomnia, which manifests itself as a feeling of disturbed, light sleep, or poor sleep quality, even though the duration of sleep may appear normal.
Psychological factors such as mood disorders, lifestyle factors such as alcohol, tobacco, and caffeine intake, and behaviors associated with poor sleep hygiene can all be "culprits" that lead to non-restorative sleep. But there is no clear evidence that vitamin D deficiency is the main cause of "not getting enough sleep."
Regarding other types of insomnia symptoms, there is some research that suggests that vitamin D deficiency may be associated with insomnia and poor sleep quality. For example, one study found that people with chronic insomnia had significantly lower serum levels of vitamin D than healthy people. However, these findings are not entirely consistent.
In 2021, Norway conducted a randomized controlled clinical study of vitamin D supplementation for 4 months in 189 people with vitamin D deficiency. The results showed that vitamin D supplementation did not significantly improve sleep levels.
Another review and meta-analysis study conducted in 2022 explored the effects of vitamin D supplementation on sleep quality. The results of this study showed that vitamin D supplementation was associated with a decrease in sleep index compared with placebo, but the certainty of the evidence was only moderate. In addition, the effects of vitamin D supplementation on sleep difficulties and disorders have not been consistent.
Overall, although vitamin D deficiency is associated with insomnia, vitamin D supplementation has no direct effect on preventing or treating insomnia.
How to improve sleep?
There are many and complex factors affecting sleep, if from the perspective of diet and lifestyle, it is recommended to start from the following aspects:
In order to maintain a healthy and good night's sleep, we should pay attention to eating a varied diet and balanced nutrition. Don't eat too much spicy and irritating food for dinner, and don't eat too late. It is best not to eat within three hours before going to bed. At the same time, do not go to bed hungry, you can choose some starch-based foods to fill your stomach.
Image source: Draft design
Don't drink, smoke, or eat caffeinated foods before bed. Drinking alcohol can affect the quality of sleep, smoking will make you more excited and difficult to fall asleep, and sensitive people should avoid coffee, tea, milk tea, cola, chocolate and other caffeinated foods and beverages may make it difficult for caffeine-sensitive people to sleep.
Strenuous exercise should not be done before going to bed. Proper bedtime exercise can increase deep sleep, ensure sleep continuity, and improve sleep efficiency.
However, if you exercise too vigorously before bedtime, you may put the body in a state of excitement, making it difficult to fall asleep. In addition, behaviors such as taking a hot shower, turning off the lights, staying away from screens such as mobile phones, playing fewer games and watching fewer movies can all help you fall asleep.
How to supplement with vitamin D?
Although vitamin D supplementation does not have a direct effect on improving sleep problems, it is still important for human health.
There are two main ways for humans to obtain vitamin D:
First, the skin is irradiated by ultraviolet rays in the sun, and it is transformed into vitamin D₃, which can be carried out more outdoor activities, and when the ultraviolet rays are not strong, it will be exposed to the sun for about 10~20 minutes;
The second is obtained by ingesting food, which can be supplemented by animal foods rich in vitamin D, such as dairy products, salmon, mackerel and sardines.
In addition, you can also take some vitamin D supplements.
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Cover of this issue:
Source | People's Network Science Popularization, Popular Science Chinese Editor| Luo Hangmei, ed Luo Hang Proofreading | Yu Zongrong, Li Tiande, Chen Shengxing, ed Yu Zongrong Statement | The source network of the data, and only used for popular science public welfare publicity, such as invasion and deletion.
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