Magnesium
Magnesium is perhaps the most important vitamin or mineral when it comes to sleep. It plays a key role in the bodily function that regulates sleep and studies have shown that sleep suffers without optimal vitamin intake.
Neil Levin, a clinical nutritionist at NOW Foods, agrees that morning is best for multivitamins and any B vitamins. “Multivitamins tend to do best when taken earlier in the day, as the B vitamins in them might stimulate metabolism and brain function too much for a relaxing evening or before bed,” Levin says.
Combining multiple supplements or taking higher-than-recommended doses can increase the risk that they can cause harm, said Kitchin. "You really can't get toxic doses of nutrients through food, but you can absolutely get toxic doses through supplements," Kitchin said.
So, get enough vitamin D—just take it in the morning or afternoon. At night, take supplements that support sleep quality and muscle relaxation, like magnesium and melatonin (which you'll find in soothing, sippable Bulletproof Sleep Collagen Protein).
There's no set time of day that's best to take vitamin D supplements. Some people say taking vitamin D supplements at night is an insomnia risk. There's no research to confirm this, but you might want to take your supplement earlier in the day if you think it's screwing with your sleep.
Umeda recommends taking the supplement about 30 minutes before bedtime. And don't take more than the recommended amount. More won't help you sleep better, but it may cause stomach upset. While magnesium might improve your slumber, it's no substitute for a good sleep routine, Dr.
The time of day that you take a vitamin doesn't affect how well your body will absorb its properties. The main thing to consider is whether you're taking the vitamin with food or not. Since fat-soluble vitamins are better absorbed with food, you might want to plan to take such vitamins close to meal or snack times.
However, taking your supplements at night isn't a good practice because your digestion and metabolism slow down when you're asleep. This means that when you take vitamins at night, they are not absorbed as efficiently as during the day.
One study of older adults with insomnia found that magnesium supplementation at a dose of 500 milligrams daily for eight weeks helped them fall asleep faster, stay asleep longer, reduced nighttime awakenings, and increased their levels of naturally circulating melatonin.
Can you take vitamin D and magnesium together? Yes. In fact, it's probably best to take both together. Because so many people have low magnesium levels, vitamin D supplements on their own aren't very helpful for a large portion of the population.
Don't use calcium, zinc, or magnesium supplements at the same time. Also, these three minerals are easier on your tummy when you take them with food, so if your doctor recommends them, have them at different meals or snacks.
Magnesium can be taken at any time of the day. Many people prefer to take supplements earlier in the day, such as with breakfast or lunch. Taking your magnesium supplement with a meal can also help prevent any stomach upset.
A new review published in The Journal of the American Osteopathic Association found vitamin D can't be metabolized without sufficient magnesium levels, meaning vitamin D remains stored and inactive for as many as 50 percent of Americans.
Magnesium assists your body in regulating zinc levels, but high intakes of zinc can be detrimental to magnesium absorption – only abnormally high doses (around 142 mg of zinc per day) will reduce magnesium absorption.
Vitamin C (ascorbic acid) supplements.
Taking vitamin B-12 with vitamin C might reduce the available amount of vitamin B-12 in your body. To avoid this interaction, take vitamin C two or more hours after taking a vitamin B-12 supplement.