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Can I Take Vitamin D at Night?

Vitamin D is one of the most important vitamins you need. There are several factors that could affect vitamin D effectiveness. The most important factors are when and how can I take vitamin D? The interesting question now is, Can I take vitamin D at night? find your answer in this article.

Overview | Importance | When to take vitamin D | How to take vitamin D

General overview

Vitamin D (cholecalciferol) is one of the most important vitamins for good and normal health. 

It is one of the fat-soluble vitamins. This means you need a fat-containing diet when administering vitamin D in order to get a chance to be absorbed.

However, it exists in low concentration in your diet. Hence, many people suffer from vitamin D deficiency. It is essential for your health to take vitamin D as a nutrition supplement to balance your diet insufficiency. 

Moreover, Vitamin D in the form of cholecalciferol is biologically inactive. Upon administration and absorption, it is rapidly metabolized firstly in the liver into 25-hydroxy vitamin D (25OHD). Further hydroxylation of 25OHD occurs in the kidney to yield the dihydroxy form 1,25-dihydroxy vitamin D (1,25DOHD). This final form is the most potent and biologically active form of vitamin D (Ref).

Vitamin D deficiency (25OHD) remains a major health problem it affects about one billion around the world (Ref).

People with Vitamin D deficiency usually suffer from general fatigue and muscle pain.

Most researchers agree that (Ref) :

  • When the blood level of 25OHd is below 20 ng/ml it is considered to be deficient.
  • When it is between 21-29 ng/ml it indicates insufficiency.
  • If the level exceeds 30 ng/ml it is considered a sufficient level.
  • Despite the natural diet doesn’t contain a sufficient amount of vitamin D. Hence, vitamin D supplements become essential to avoid vitamin D deficiency problems.
Vitamin D Rich Foods

Importance of vitamin D

  • Vitamin D is an essential vitamin for the regulation of calcium and phosphorous absorption and metabolism which are crucial elements for healthy bones (Ref).
  • It plays an important role in building your immune function, and in cancer prevention.
  • Also, it is required for pregnant women to decrease the risk of pre-term labor, and preeclampsia and to improve their maternal vitamin D status (Ref).

Now, to avoid vitamin D deficiency problems, learn more about when to take vitamin D? and how to take it?

When to take Vitamin D (at day or night)

When it is administered during the day (The morning dose):

  • Vitamin D is among the vitamins that are more effective when administered at a certain time. This is because the time at which you take it could affect its absorption.
  • Vitamin D (cholecalciferol) needs sunlight exposure to be activated in your body to the biologically active form dihydroxy vitamin D.
  • In the USA about 42% of adults have vitamin D deficiency problems. This may be attributed to the lack of exposure to sunlight and low consumption of vitamin D-rich diets.
  • The baseline vitamin D sufficiency is 30 ng/ml in blood (Ref). In the USA, researchers measured the blood level of 25-hydroxyvitamin D (the blood biomarker of vitamin D) in adults. They found that the 25-hydroxyvitamin D was around 18- 22 mg/ml at the end of winter. While this value increased in summer to about 29 ng/ml (Ref). Both two values are below the required baseline of vitamin D. These results clearly indicate the importance of sun exposure for vitamin D activation.
  • A study published in the International Journal of Occupational Medicine and Environmental Health studied the relationship between night work and the level of 25OHD. They reported that the level of vitamin D (25OHD ) in females working at night was significantly lower than in those working during the day. 
  • Many people prefer to take vitamin D in the morning during breakfast. This could help them to remember the daily dose.
  • Vitamin D during breakfast is the best choice, especially when you take it with healthy fats like avocados.
  • In case you forget your dose, don’t panic, you can take double the dose the next day.

When vitamin D is administered at night (The night dose):

  • A study showed that taking vitamin D at night may disrupt sleep. When you take a high dose of vitamin D at night, your body may feel it is daytime and you need to wake up for sunlight. 
  • Studies revealed that there is a relationship between vitamin D blood level and melatonin hormone secretion. Melatonin is a  hormone that regulates your sleep and wake cycles (Ref).
  • Studies showed that vitamin D could reduce the production of melatonin. Thus, it could lead to a sleep disorder (Ref). 
  • On the other hand, A recent 2020 study showed that vitamin D plays a role in sleep regulation. Its deficiency could lead to sleep disorders. However, scent evidence supports the role of vitamin D in the prevention and treatment of sleep disorders.
  • A study reported that there is a significant relationship between Vitamin D deficiency and sleep disorder. 

Now, you get confused!! Right? It is not clear to you whether vitamin D improves sleep disorders or causes a sleep disturbance?? let us explain this matter.

  • Studies proved that there is a bidirectional relationship between vitamin D blood level and sleep.
  • In case of vitamin D deficiency (suboptimal vitamin D blood level), sleep disorders appear as low sleep quality and short duration of sleep.
  • Moreover,  inadequate sleep is attributed to vitamin D deficiency (Ref)
  • On the other hand, a higher dose of vitamin D  could lead to sleep disorders by altering melatonin secretion (Ref).
  • So optimal and sufficient level of 25OHD in your blood is essential for optimal sleep manner. 

How to take vitamin D?

  • Vitamin D is a fat-soluble vitamin. Its absorption improved when you take it with fat-containing meals. 
  • A study proved that a higher blood concentration of vitamin D is obtained when it is administered with your largest meal. 
  • Also, vitamin D absorption is best when administered with food containing high-fat content. For example, avocado, nuts, and seeds. 


  • Vitamin D is administered in an inactive form, it requires essential exposure to sunlight to be activated to the abiological active form.
  • Vitamin D should be administered with a fat-rich diet in order to ensure better absorption.
  • It is best to take vitamin D in the morning, to ensure activation during the day when you get sun. Moreover, the night dose could affect your sleep by suppressing the production of melatonin (sleep hormone). Hence the night dose could negatively affect your sleep.