Vitamin D for Better Sleep?

Seasonal insomnia typically strikes at about this time of year. As the days get shorter, we’re exposed to shorter periods of sunlight, which can alter circadian rhythms and interfere with sleep.

A related problem has to do with our need for vitamin D, which may not be met in low sunlight conditions. Recent publications explore the effects of low levels of vitamin D on sleep, making supplements a good option in the cold weather.

Seasonal insomnia may be driven by vitamin D deficiencySeasonal insomnia typically strikes at about this time of year. As the days get shorter, we’re exposed to shorter periods of sunlight, which can alter circadian rhythms and interfere with sleep.

A related problem has to do with our need for vitamin D, which may not be met in low sunlight conditions. Recent publications explore the effects of low levels of vitamin D on sleep, making supplements a good option in the cold weather.

A Relationship Between Sleep and Vitamin D

It’s well established now that lack of exposure to sunlight has a negative effect on sleep. Interest in the relationship of vitamin D to sleep is relatively new, yet preliminary evidence suggests that low levels of D are associated with short sleep duration, a frequent complaint of people with insomnia. A recent meta-analysis of studies of vitamin D deficiency and sleep disorders also found an association between low levels of D and poor sleep quality.

Levels of vitamin D fluctuate seasonally. Our bodies make most of the vitamin D we need when our skin is exposed to sunlight, and typically there are fewer opportunities for sunlight exposure in the colder months of the year. Thus insufficient vitamin D could be a factor in seasonal insomnia.

Vitamin D Supplements: Will They Improve Sleep?

While a few studies document improved sleep as a result of higher levels of vitamin D, a causal relationship between vitamin D supplementation and better sleep has not been definitively established. However, for a host of health reasons including sleep — avoidance of infectious, autoimmune and neurological diseases, as well as neuromuscular disorders and increased pain sensitivity — vitamin D deficiency is a condition we should try to avoid.

It’s a good idea to pay attention to recommended dietary allowances — expressed in international units (IU) per day — especially in the wintertime. They were established by the Institute of Medicine based on vitamin D’s importance to the development and maintenance of healthy bones. Subsequently the Endocrine Society established recommended dietary allowances for people at risk for vitamin D deficiency. Here’s a table showing both sets of guidelines for daily intake of vitamin D:

Infants Ages 1–18 years Ages 19–70 years Ages 71 & older
Institute of Medicine 400 IU/day 600 IU/day 600 IU/day 800 IU/day
Endocrine Society 400-1000 IU/day 600-1000 IU/day 1500-2000 IU/day 1500-2000 IU/day

Foods Containing Vitamin D

Up to 80% of our D requirement may come from the complex metabolic processes triggered with exposure of the skin to sunlight. But we also get vitamin D from a limited number of foods. Some foods naturally contain D and other foods are fortified with it. Here are some common foods containing vitamin D and approximate amounts:

  • 3.5 oz salmon, fresh (wild): 600–1,000 IU
  • 3.5 oz salmon, fresh (farmed): 100–250 IU
  • 3.5 oz salmon, canned: 300–600 IU
  • 3.5 oz sardines, canned: 300 IU
  • 3.5 oz mackerel, canned: 250 IU
  • 3.5 oz tuna, canned: 236 IU
  • 3.5 oz shiitake mushrooms: 100 IU
  • 1 egg yolk: 20 IU
  • 3.5 oz beef liver, braised: 12–30 IU
  • 8 oz fortified milk or yogurt: 100 IU
  • 8 oz fortified orange juice: 100 IU
  • 3 oz fortified cheese: 100 IU

Breakfast cereals and soy products are also often fortified with vitamin D.

At Risk for Vitamin D Deficiency

You’re more likely to have low levels of vitamin D in these conditions:

  • You get little exposure to sunlight. This may occur if you live in a northerly latitude, spend all or most of your time indoors, habitually wear clothing covering your entire body or cover up with sunscreen all the time. (An SPF of 30 or higher, which confers important protection from cancer, decreases vitamin D synthesis in the skin by more than 95%.)
  • You have dark skin. Dark skin confers natural protection from harmful radiation from the sun but also makes it harder to synthesize vitamin D. Longer periods of sun exposure are required for sufficient vitamin D production to occur.
  • You’re vegan. Most natural sources of vitamin D are animal based.
  • You’re obese. Individuals with a body mass index of 30 or higher often have low blood levels of vitamin D.
  • You’re pregnant or lactating. Pregnant and lactating women may have decreased levels of vitamin D as well.
  • You’re older and have a history of falls and/or fractures. Older adults are somewhat less efficient at synthesizing vitamin D via sunlight exposure.

Vitamin D Supplementation

To remedy low levels of vitamin D, or to maintain adequate levels throughout the winter, take a vitamin D supplement. Take your daily supplement with a meal containing fat, as this will increase vitamin D absorption.

Supplementation and adequate exposure to sunlight (or bright light supplied by a light box) at the approach of the holidays and through the winter may help to protect you from the bane of seasonal insomnia.

Q&A: Light and Vitamin D for Seasonal Insomnia

Some people have trouble sleeping when the days get shorter. I’m one of them and so is Gabriel, who recently wrote in wondering how to improve his sleep:

“I was born close to the equator in Brazil, and I usually don’t have problems sleeping when I’m there or during the summer time in Canada, where I live now. But winter is around the corner, and my sleeping problems have just begun again. I usually go to bed at 11 p.m. but wake up around 3 a.m. However, in the summer my wake time is 7 a.m. I feel irritated, depressed and cannot concentrate. . . Is light treatment the way to go?”

Insomnia in colder months due to lack of sunlight and vitamin DSome people have trouble sleeping when the days get shorter. I’m one of them and so is Gabriel, who recently wrote in wondering how to improve his sleep:

 

 

 

 

 

 

 

I was born close to the equator in Brazil, and I usually don’t have problems sleeping when I’m there or during the summer time in Canada, where I live now. But winter is around the corner, and my sleeping problems have just begun again. I usually go to bed at 11 p.m. but wake up around 3 a.m. However, in the summer my wake time is 7 a.m. I feel irritated, depressed and cannot concentrate. . . Is light treatment the way to go?

Lack of Bright Light

Reduced light exposure probably accounts for Gabriel’s symptoms, including his insomnia at night. People who live in northern latitudes (residents of Canada fit the bill) get less exposure to sunlight starting in the middle of fall and continuing through March or April. This can alter circadian rhythms and destabilize sleep. It may be related to seasonal affective disorder (SAD).

Especially susceptible are those who commute in the dark and work all day in windowless offices, dimly-lit warehouses, and the like. Sunlight resets the body clock to run on a 24-hour cycle. Without daily exposure to sunlight (or to the blue-enriched light emitted by a light box), circadian rhythms may go out of sync. Secretion of the sleep-friendly hormone melatonin may be delayed in the evening. (Or, as I suspect in my case, it may begin too early, causing me to drift off and—like Gabriel—wake up too early.)

Sleep-related symptoms vary from person to person, but here are some you might recognize in yourself:

  • Sleeping more or less than usual
  • Trouble falling asleep or a tendency to fall asleep earlier than normal
  • Having an erratic sleep schedule
  • Trouble getting out of bed
  • Feeling groggy in the morning and tired during the day

Increase Your Exposure to Bright Light

Getting a healthy dose of exposure to sunlight every day may solve the problem. Take a walk outside or move your desk to the sunny side of the room.

Light treatment with a light box can also work. Light emanating from a light box mimics the blue-enriched light from the sun. Set it up so the light floods your work space but you’re not looking directly into it: this will likely increase your alertness and help stabilize your sleep. The amount of light exposure needed varies from one person to the next.

Get Enough Vitamin D

Another thing to consider is taking vitamin D supplements. Emerging evidence suggests that lack of the sunshine vitamin may contribute to insomnia and sleep problems in the wintertime, when the days are shorter and more overcast. The latest study published on this topic appeared last February, and the results strongly suggest that sufficient levels of vitamin D are important to maintaining healthy sleep. Among over 3,000 men ages 68 years and older,

  • lower serum vitamin D levels were associated with higher odds of short sleep duration (less than 5 hours a night), and
  • the sleep of men with low levels of vitamin D was less efficient.

The human body produces vitamin D with exposure to sunlight. So people living in northern latitudes are more likely than others to develop a vitamin D deficiency in the wintertime. Other risk factors for vitamin D deficiency are these:

  • Being female or older
  • Being obese or underweight
  • Having a physically inactive lifestyle
  • Having dark skin (The pigment melanin reduces the ability of the skin to manufacture vitamin D with exposure to sunlight.)

While the relationship between sleep and vitamin D is not fully understood, existing research suggests it’s probably a good idea to take a supplement, especially if during the colder months your sleep takes a turn for the worse. The Institute of Medicine recommends 600 international units (IUs) daily for people up to 70 years old and 800 units for people 71 years and older. But the safe upper limit for vitamin D is currently 4,000 IUs a day.

Do you have trouble sleeping in the colder months of the year? If you’ve tried using a light box, has it helped?

Vitamin D: Sleep on It

Could our sleep problems have anything to do with a deficiency of vitamin D?

There is no research showing a definitive link between insomnia and low levels of vitamin D. Yet studies do suggest that those of us with sleep problems might do well to examine our lifestyles and our diets to make sure we’re getting enough of the sunshine vitamin.

Could our sleep problems have anything to do with a deficiency of vitamin D? A story about insomnia and vitamin D deficiency recently caught my eye, and a quick search of Pubmed turned up these article titles: sunshine-vitamin

None of these studies shows a definitive link between insomnia and low levels of vitamin D. Yet they do suggest that those of us with sleep problems might do well to examine our lifestyles and our diets to make sure we’re getting enough of the sunshine vitamin.

Vitamin D: How We Get It

Our bodies produce vitamin D with exposure to sunlight. We can also get it by taking vitamin D supplements (it is often combined with calcium) and by eating these foods:

  • Fish and fish liver oils
  • Fortified cereals
  • Fortified soy products
  • Salami, ham, sausages, and beef liver
  • Fortified dairy products
  • Egg yolks

Causes of Vitamin D Deficiency

You’re at higher risk for vitamin D deficiency if:

1)  You get inadequate exposure to sunlight. This may occur because you’re homebound, have an indoor job, live in a northern latitude, or cover up or wear sunscreen all the time.

2)  You’re vegan. Most natural sources of vitamin D are animal based.

3)  You have dark skin. The pigment melanin cuts down on the skin’s ability to produce vitamin D when exposed to sunlight.

4)  You are obese. People with a body mass index of 30 or higher often have low blood levels of vitamin D.

Recommended Daily Allowances

A simple blood test can determine definitively whether you’ve got a vitamin D deficiency, and if you suspect you do, pursue it with your doctor. But we can all make sure our daily intake of vitamin D falls within the Institute of Medicine’s current RDAs:

  • 600 international units (IUs) for people aged 1 to 70
  • 800 IUs for people older than 70

Back to the vitamin D supplement studies cited above: the subjects whose sleep improved took much higher dosages of vitamin D than the current RDAs. The safe upper limit for vitamin D is currently 4,000 IUs a day.