Himalayan salt lamps are crystals carved from amber-colored rock salt, hollowed out to fit a lightbulb inside. When you light them they give out a warm, reddish-pink glow.
Sellers of these decorative pieces say they do more than light up a room. They claim the lamps can boost mood, improve sleep, ease allergies, help people with asthma breathe better, and clean the air, among other benefits.
The claims sound impressive. Yet the scientific evidence to back them up is scarce.
What Are Himalayan Salt Lamps?
The salt in these lamps comes from the Himalayas, a mountain range that stretches about 1,500 miles across Pakistan, India, Bhutan, and Nepal.
True Himalayan salt lamps come from the Khewra Salt Mine in Pakistan. The salt this mine produces has a reddish, pink, or off-white color.
There are plenty of fake ones sold online. The real versions are fragile and give off a dim light. The phony products are tough to break and glow brightly.
What Are Negative Ions?
Advocates say the lamps work in two ways:
Pull in particles. They lamps supposedly attract allergens, toxins, and pollutants to their surface.
Possibly release negative ions. Some people believe negative ions in the air have health benefits.
Ions are molecules that have undergone a change in charge. Negative ions have gained an electron. Positive ions have lost one.
Ions are all around us. Some come from particles from outer space that make their way to earth. Others form closer to home, from radiation, sunlight, lightning, or the collision of water droplets in a waterfall.
Some people say they feel more refreshed and clear-headed after a storm, a feeling they believe is due to the amount of negative ions in the air. Commercial ionizers and purification systems also produce negatively charged ions to create cleaner and more comfortable indoor spaces.
Himalayan salt lamps supposedly produce negatively charged ions while water molecules from the air attract to -- and then evaporate from -- the warmth of its surface. Those who believe in the health benefits of these lamps give negative ions much of the credit.
What the Science Shows
Although a few studies show some benefits from negative ions, the evidence that salt lamps improve health is lacking.
Mood and sleep. Some people believe that positive ions in the air increase anxiety, irritability, and unpleasant feelings. They say that negative ones ease stress, anxiety, and depression, and improve overall well-being.
Studies with mice and rats suggest that high amounts of negative air ions alter levels of serotonin -- a chemical that contributes to feelings of well-being.
In some human studies, negative ions at high concentrations did lessen depression slightly, but they didn't have much of an effect on anxiety levels or sleep.
A very small study shows that people did better on thinking skills tests when they were in a room where the paint on the walls had a high concentration of total air ions (both positive and negative ions). But the paint had no effect on their general well-being.
Asthma and allergies. The notion that that negative ions may improve breathing has led to a few studies on the topic. In most of them, negative ions didn't ease breathing or asthma symptoms. They also didn't lower inhaler use in children and adults with chronic asthma either.
Cleaning the air. Negative ions do have some ability to clean harmful particles from the air. When ions build up on bacteria or pollen, they neutralize the pollutants. Studies suggest that negative and positive ions may kill germs, though exactly how isn't clear, and some experts say the germ-killing may be due to other reasons. In any case, there's no evidence salt lamps have this effect.
The Bottom Line
Though the claims sound promising, so far no one has proved that Himalayan salt lamps release negative ions, let alone enough to have any impact on health. Most of the research so far has used negative ions from other sources, not lamps.
In a couple of small studies on rats and mice, contact with a salt lamp had antidepressant and anti-anxiety effects. That doesn't mean the lamps would have the same effect on humans. Researchers would have to test the theory.
Though a small amount of pollutants in the air might stick to salt rock, these rocks don't have anywhere near the filtering ability of, say, charcoal, a common component of air filters.
A Himalayan salt lamp might bring a nice decorative touch and a warming glow to your space, but there's no research right now that says it will improve your health in a big way.