Tea is a staple in the daily routines of many across the UK, with approximately 100 million cups consumed every day. While this beloved beverage offers health benefits, particularly in reducing the body’s primary stress hormone, experts caution about the timing to avoid disrupting sleep cycles.
Mike Kocsis, founder and hormone health specialist at Balance My Hormones, explains the dual role tea plays. “Cortisol, known as the stress hormone, should naturally decline as the day ends, while melatonin, the sleep hormone, rises in the evening. Tea influences both sides of this hormonal balance; its plant compounds aid cortisol reduction, but its caffeine content can suppress melatonin production,” he said.
Highlighting recent scientific findings, Kocsis shared, “A randomised double-blind trial at University College London had men consume four cups of black tea daily for six weeks. A control group received a placebo with identical caffeine levels. Following a stressful event, cortisol levels in the tea drinkers dropped by 47% within 50 minutes, compared to a 27% reduction in the placebo group, who also reported feeling less relaxed.”
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Because caffeine was matched in both drinks, the enhanced cortisol recovery is attributed to tea-specific compounds such as L-theanine and flavonoids, rather than caffeine alone.
Regarding the impact of tea on sleep, Kocsis noted, “A standard black tea contains around 40 to 50 milligrams of caffeine - roughly half that of a typical coffee. While one cup may seem modest, multiple servings throughout the afternoon can accumulate significant caffeine levels.”
He referenced research published in Science Translational Medicine, showing that caffeine equivalent to a double espresso consumed three hours before bedtime delayed the body’s melatonin rhythm by about 40 minutes. This demonstrates caffeine’s physical effect on the internal clock rather than simply creating a feeling of alertness.
Additional sleep studies further illustrate that even caffeine taken six hours before bed can reduce total sleep time by over an hour, emphasising why several afternoon cups can affect sleep quality.
Based on these insights, Kocsis recommends, “For those who typically go to bed around 10.30pm to 11pm, it is best to have the last caffeinated tea by 4pm. This allows at least six hours without caffeine before sleep, while still enjoying morning and early-afternoon tea with its beneficial compounds.”
He suggests switching to decaffeinated tea or caffeine-free herbal infusions after 4pm, as decaffeinated versions often retain the helpful L-theanine and flavonoids.
Recognising individual differences, Kocsis added, “Caffeine sensitivity varies due to factors like age, genetics, and medication. Some people may need to stop caffeine earlier, while others can tolerate later consumption. Starting at 4pm is practical, but adjust earlier if sleep issues persist.”
Finally, he emphasised that while tea can contribute to a more relaxed evening, it is not a cure-all. “If poor sleep, low energy, or mood problems continue for months despite adjusting tea habits, the next step should be professional hormone testing rather than self-diagnosis,” Kocsis advised.
Understanding the balance between the benefits and drawbacks of tea’s caffeine can help tea lovers enjoy their favourite drink without sacrificing restful sleep.