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4 Supplements That Could Be Wrecking Your Sleep, According To A Neurologist: Vitamin D, More

June 27, 2025 by Abigail Connolly

 
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When you start taking a certain supplement, some people may believe that it’s best to start taking it at nighttime, before bed. While that may apply to some, it’s not always the case.

A neurologist and TikTok content creator, Dr. Alan Mandell, made a video about three supplements that “you shouldn’t take before bed,” as they can disrupt your sleep. Not getting enough sleep has a significant impact on our bodies, as it can cause trouble focusing, stress, weight gain, and other irritating symptoms. Read more about Dr. Mandell’s three vitamins that should be avoided at bedtime below.

 Vitamin B-12

Dr. Mandell says that vitamin B-12 is "vital for energy production and brain function," but that it should be taken at another time besides right before bed. In fact, many people take B-12 because they have issues with fatigue or trouble focusing, so it would make sense not to take it before trying to get a good amount of sleep at night.

"B-12 can be very stimulating to the central nervous system, and that can disrupt your sleep," he adds.

Vitamin D

Vitamin D is often called the 'sunshine' vitamin, and is popular for helping out our bone and immune health. Many elderly people take it for osteoporosis, but anyone can begin taking it, especially if they've been told they have a deficiency by their doctor.

"Vitamin D is essential for bone and immune health," explains Dr. Mandell.

"But vitamin D can interfere with melatonin production, the hormone that regulates our sleep, potentially leading to difficulty falling asleep and staying asleep."

Vitamin C

Many of us are taking vitamin C these days, as it's known to be very supportive of our immune systems, and people tend to get in as much as possible in fear of getting a cold. However, taking it before bed can cause issues, and they don't have to do with your energy levels.

"Vitamin C is also known for boosting your immune system, but [it] can cause gastrointestinal discomfort, and if you're taking this before lying down, in some cases, this may give you that mild stimulatory effect, making it challenging to relax before sleep," notes Dr. Mandell.

Vitamin E

Unfortunately, while vitamin E can be very beneficial to our hair and skin, it can also cause some stomach issues when taken before bed.

"Vitamin E sometimes can cause gastrointestinal issues as well," says Dr. Mandell. "It can be uncomfortable and disruptive during the night."

The Bottom Line

If you want the best results from these vitamins and supplements and don't want to risk losing any sleep, Dr. Mandell suggests taking them "earlier in the day." For instance, you can kick off your morning by taking your supplements along with your daily cup of coffee.

"[They] will give you lots of energy, keep you focused, and most importantly, keep you healthy," he adds.

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