Will drinking tea affect my sleep?

• Multiple statistical observations of caffeine content in tea:

When it comes to the question of whether or not tea affects sleep, the most straightforward evidence is the amount of caffeine in the tea broth. However, the definition of a "cup of tea" varies slightly from one research organization to another, so the data will show a range rather than a single figure.

United States USDA (2020) 的 FoodData Central databases, usually in the form of For every 100 g (approx. 100 ml) of tea broth brewed To calculate the caffeine content of a cup of tea in units of If the caffeine content of a cup of tea is calculated in 240 ml(American Mug) The benchmarks are as follows:

• Green tea: 20-40 mg
• Oolong tea: 15-30 mg
• Black tea: 30-50 mg

Mayo Clinic (USA) The clinical information states that a cup of tea is about 240 ml:

• Green tea: 30-50 mg
• Oolong tea: about 30-40 mg
• Black tea: 40-70 mg

European Food Safety Authority (EFSA, 2015) In the Caffeine Safety Opinion, which lists each cup of 200 ml Tea SoupThe average content of the

• Green tea: about 20-40 mg
• Oolong tea: about 30 mg
• Black tea: about 40-60 mg

Tea and Beverage Crop Improvement Plant, Ministry of Agriculture, Taiwan The study has also examined the range of different tea types (200 ml of brewed tea broth):

• Green tea: 25-45 mg
• Oolong tea: 20-35 mg
• Black tea: 40-55 mg

📊 Consolidate the above data (based on 240 ml cup):

• Green Tea: 20-50 mg (refreshing, medium pick-me-up)
• Oolong tea: 15-40 mg (medium, varies by roasting level)
• Black tea: 40-70 mg (highest in tea)

🌱 Major Factors Affecting Caffeine Content of Tea Leaves

The differences in the above figures cannot be determined solely by the "type of tea", but must be observed from multiple factors such as the environment of the tea plant, the season, the harvesting, the craftsmanship, and the brewing process, and so on.

Here are seven factors that explain why the same tea can have different refreshing sensations:

1. Planting environment (altitude):

• Takayama Tea Garden: Photosynthesis is limited due to short days, low temperatures, and cloudiness, and tends to be lower in caffeine.
• Flatland Tea Garden: Strong sunlight, long exposure time, high temperature, relatively high caffeine content.

2. Seasonal Factors

• Spring and winter tea:Because the sunlight is weaker and shorter, and the temperature is lower, the tea buds grow slower and the caffeine accumulation is lower.
• Summer and Fall TeaThe tea tree grows rapidly due to the long sunshine and high temperature. In order to resist pests and environmental pressure, the caffeine content of the tea tree is on the high side.

3.Tea tree varieties:

• Large Leaf: Taiwan Tea No. 18 (Red Jade), AssamGenetically high in caffeine, suitable for making black tea.
• Small-leafed species: Green heart oolong and other bush tea trees, with low coffee content, are the main varieties of tea in Taiwan.

4.Picking part

• Young shoots or leavesCaffeine is a natural defense for the tea tree and is used to protect the buds from pests. Green tea and black tea are mainly harvested from the young leaves.
• Lao Ye: The caffeine content is significantly lower.

5.Process Craftsmanship

• Roasting processTea leaves are roasted at high temperatures to sublimate the caffeine. The high temperatures refine the caffeine and separate it from the tea leaves, thus reducing some of the caffeine content, e.g. Iced Oolong Tea and Tieguanyin are good choices, and the tea broth will be more rounded and less irritating under the roasting.

6.Brewing Method

• quantity of tea: The more tea you put in, the stronger the tea and the higher the caffeine content.
• Water TemperatureHigh-temperature brewing releases the most; low-temperature or cold brewing releases only about half as much as hot brewing.
• Soak TimeThe longer the time, the more caffeine is dissolved.

✅ Conclusion

1. High mountain tea ＞ Flatland tea (less sunshine)

2. Spring/Winter ＞ Summer/Autumn (less sunshine)

3. Small-leafed species ＞ Large-leafed species (less abundant)

4... Roasted ＞ Unroasted (can refine caffeine)

5. Low temperature cold foam ＞ hot foam (reduced release)

6. Mature leaves ＞ Young leaves

6. Black tea ＞ Oolong tea ＞ Green tea (theaflavors and theabolites reduce caffeine stimulation)

I. Individual Physical Differences

     Even if you are drinking the same tea, everyone feels differently. This has to do with Genetic and Physical DifferencesRelevant.

• Genetic metabolic differences:
  The enzyme CYP1A2 is responsible for metabolizing caffeine in the human body. Studies have shown that genotype affects the rate of metabolism, causing some people to be sensitive to caffeine, which in turn affects sleep.
• Age and Sensitivity:
  As we age, our metabolism declines and our sensitivity to caffeine increases, so more and more people are finding that "drinking tea doesn't affect sleep when you're young, but you tend to have insomnia when you're older".

Tea drinking time and sleep effects

In addition to the tea plantand physical fitness.Time to Drink Tea It's also important.

• Effects of drinking tea 6 hours before bedtime:
  A sleep study in the United States found that caffeine intake even 6 hours before bedtime shortened the duration and depth of sleep.
• Reduce irritation by pairing it with food:
  Drinking tea on an empty stomach results in faster absorption of caffeine and a stronger stimulus; if consumed with a meal, the caffeine is absorbed more slowly and the effect is lessened.