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Green Tea (240ml / 8oz)

Caffeine Half-Life Analysis

For: Elderly (65+)
28
mg Caffeine
6.5
Hour Half-Life
~N/A
Hours to Sleep-Safe
300
mg Daily Limit

trending_down Caffeine Decay Timeline

How 28mg caffeine clears from your system with a 6.5-hour half-life

Time Elapsed Caffeine Remaining % of Original Status
Now (consumption) 28.0 mg
100.0% 		Minimal
After 1 hour 25.2 mg
89.9% 		Minimal
After 2 hours 22.6 mg
80.8% 		Minimal
After 3 hours 20.3 mg
72.6% 		Minimal
After 4 hours 18.3 mg
65.3% 		Minimal
After 5 hours 16.4 mg
58.7% 		Minimal
After 6 hours 14.8 mg
52.7% 		Minimal
After 8 hours 11.9 mg
42.6% 		Minimal
After 10 hours 9.6 mg
34.4% 		Cleared
After 12 hours 7.8 mg
27.8% 		Cleared
After 16 hours 5.1 mg
18.2% 		Cleared
After 20 hours 3.3 mg
11.9% 		Cleared
After 24 hours 2.2 mg
7.7% 		Cleared

health_and_safety Health Insights for Elderly (65+)

⚠️ Important Health Consideration

After age 65, liver enzyme efficiency decreases, extending caffeine's half-life. Sensitivity to caffeine's effects on sleep also increases.

Daily Limit Calculation

  • • Recommended daily limit: 400mg of caffeine
  • • Caffeine per serving: 28mg
  • • Servings until limit: 14.3 servings

Avoid caffeine after midday. Consider reducing total intake as sensitivity increases.

Sleep Quality Impact

Caffeine blocks adenosine receptors in the brain, preventing the buildup of sleep pressure. Even when you don't feel "wired," residual caffeine can reduce deep sleep quality by up to 20%.

>100mg
May disrupt sleep
50-100mg
Reduced deep sleep
<50mg
Minimal impact

science How Caffeine Half-Life Works

Half-life is the time required for the body to eliminate 50% of a substance. For caffeine, this primarily occurs in the liver through the CYP1A2 enzyme system.

With a half-life of 6.5 hours for elderly (65+), caffeine follows exponential decay:

  • After 6.5 hours: 50% remains (14.0mg)
  • After 13.0 hours: 25% remains (7.0mg)
  • After 19.5 hours: 12.5% remains (3.5mg)
  • After 26.0 hours: 6.25% remains (1.75mg)

The elderly (65+) category has a slower metabolism compared to healthy adults (5 hours baseline). After age 65, liver enzyme efficiency decreases, extending caffeine's half-life. Sensitivity to caffeine's effects on sleep also increases.

warning Please Note

Avoid caffeine after midday. Consider reducing total intake as sensitivity increases.

Compare Other Drinks

Brewed Coffee (240ml / 8oz) 95mg Espresso (30ml / 1oz shot) 63mg Red Bull (250ml / 8.4oz) 80mg Monster Energy (473ml / 16oz) 160mg

Compare Conditions

Healthy Adult 5.0h Smokers 3.0h Pregnancy 10.5h Birth Control Users 7.5h Liver Impairment 12.0h Fast Metabolizers (Genetic) 3.5h

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About Green Tea (240ml / 8oz)

Brewed green tea

Note: Contains L-theanine which modulates caffeine's effects

help Frequently Asked Questions

How long does Green Tea (240ml / 8oz) caffeine last for elderly (65+)?

For elderly (65+), the caffeine half-life is approximately 6.5 hours. This means that 28mg of caffeine from Green Tea (240ml / 8oz) will take about 6.5 hours to reduce to 14mg, and 13.0 hours to drop to 7mg. Full clearance (below 10mg) takes approximately 9.7 hours.

When should I stop drinking Green Tea (240ml / 8oz) to sleep well?

If you plan to sleep at 10 PM, you should consume your last Green Tea (240ml / 8oz) by any time - caffeine level is low. This allows approximately sufficient hours for caffeine levels to drop below the sleep disruption threshold of 100mg.

How does being in the 'Elderly (65+)' category affect caffeine metabolism?

After age 65, liver enzyme efficiency decreases, extending caffeine's half-life. Sensitivity to caffeine's effects on sleep also increases. Avoid caffeine after midday. Consider reducing total intake as sensitivity increases.