Green Tea for Insomnia: What the Science Says

Drinking green tea is known for numerous health benefits, including being protective against certain types of cancer, heart disease, liver disease, etc. (1).

And because tea is known to be a relaxing drink, it’s reasonable to question if it could help insomnia as well.

I’ve reviewed and summarized all the research I could find looking at the effects of green tea and sleep in this short post.

Does Green Tea Improve or Harm Sleep?

Tea in general has a few things that might make you think that it’s good for sleep. The main two are:

• Amino acids - Amino acids are the building blocks of protein, and tea contains a small amount. Most important, green tea is relatively high in the amino acid L-theanine, which is known to have a relaxing effect (more on that later).
• Polyphenols - The main reason that tea is good for most people are the polyphenols it contains. This includes antioxidants, which have a variety of potential health benefits.

However, there are a few aspects that may make sleep worse:

• Liquids - Consuming liquid before bed leads to sleep disturbances (i.e. waking up to urinate) (2).
• Caffeine - All "real" tea, including green tea, contains caffeine (and too much caffeine can cause insomnia). But unlike coffee, it's quite a bit lower.

Assuming you’re just having a small drink of green tea (a cup or two), the bigger potential issue is the caffeine.

Research has shown that a small amount of caffeine during the day doesn’t significantly worsen sleep, so a cup or two of green tea should be fine for most people (3). But if you get over a certain threshold, it will make it harder to fall asleep.

Drinking tea shortly before bed could be a problem, and it could also make sleep worse if you already have a high caffeine intake from other sources throughout the day like coffee or chocolate.

SummaryWhether or not green tea has a positive effect on sleep depends on how the positive and negative aspects balance out. This can vary among individuals (i.e. how sensitive they are to caffeine).

If Green Tea Has Caffeine, How Can It Improve Sleep?

So far, research has found one component in green tea, the amino acid theanine, that reduces levels of stress-related hormones (4).

Furthermore, one study in rats found that (5):

...low doses of L-theanine can partially reverse caffeine-induced reductions in slow-wave sleep; however, effects of L-theanine on caffeine-induced insomnia do not appear to increase dose-dependently.

In other words, theanine may counteract some amount of caffeine, but only up to a certain point. As a side note, there are L-theanine supplements that may help insomnia if that's all you're looking for.

SummaryGreen tea may improve or harm sleep. The caffeine in it contributes to worsening sleep, while theanine helps reduce stress and promote relaxation. The more tea you drink, the more likely that it will impair sleep.

The Effect of Low Caffeine Green Tea on Sleep

The one thing we’re missing from what we’ve looked at so far is that not every green tea is the same.

When you go to a tea retailer, there’s usually some sort of indicator of the level of caffeine in a tea:

Some green teas have a small amount of caffeine, but still a relatively high amount of theanine. These are the ones that are most likely to improve sleep.

A few studies have compared “standard” green tea with low caffeine green tea.

One study found that (6):

Sleep quality was higher in participants that consumed a larger quantity of LCGT (low caffeine green tea).

That’s a really important result, because it shows that in green teas with low levels of caffeine, the effect of the theanine more than counteracts the caffeine content.

Another study did a similar comparison in the elderly (7). The results similarly suggested that low-caffeine green tea had a moderately positive effect on sleep.

SummaryWhile more research is needed, current research does suggest that drinking a reasonable amount of green tea that's low in caffeine (or decaffeinated green tea) can improve sleep quality in most subjects.

Are Other Teas Better Than Green Tea for Sleep?

Green tea is likely the best tea for insomnia and generally improving sleep quality.

The reason that most studies focus on the effect of green tea on sleep is because it’s highest in l-theanine, which is the most important compound in this context.

Other teas (e.g. black, white, oolong) also contain some theanine and may be beneficial, but are often higher in caffeine as well.

Finally, herbal teas may have some benefits for sleep. Herbal teas are not “real” tea (from the camellia sinensis plant), but rather tea made from steeping various plants and spices. They do not contain l-theanine, but can still be relaxing (which makes it easier to fall asleep).

The evidence is much research, but there is some that suggests that the following herbal teas may have some benefit:

• Passionflower
• Chamomile
• Magnolia
• Lavender

SummaryGreen tea is likely the best tea for insomnia or sleep in general, but future research could come out that says otherwise. It’s certainly fine to experiment on your own to see how your body reacts to different types of teas.

Summary: Does Green Tea Help Insomnia?

What we’ve seen is that drinking green tea in moderate amounts is unlikely to harm sleep unless it’s done right before bed unless someone is very sensitive to the caffeine in green tea.

Additionally, green teas with low levels of caffeine have been shown to improve sleep quality, especially when compared to green teas with higher caffeine levels.

Based on the current research, it doesn’t look like green tea is a cure for sleep disorders like insomnia, but it could be a part of the solution for some people. If you wake up frequently because of the liquid, you could also try green tea extract.

Another similar option for insomnia is chamomile tea or extract.

Finally, it's low risk, just like other foods that may or may not improve insomnia like ginger or garlic.

References

1. Green tea: Health benefits
2. A practical approach to the management of nocturia
3. Risk Factors for Incident Chronic Insomnia: A General Population Prospective Study
4. Anti-stress effect of theanine on students during pharmacy practice
5. L-theanine partially counteracts caffeine-induced sleep disturbances in rats
6. Reduced Stress and Improved Sleep Quality Caused by Green Tea Are Associated with a Reduced Caffeine Content
7. Ingestion of green tea with lowered caffeine improves sleep quality of the elderly via suppression of stress