When we feel tardy and unalert, most of us take a quick trip to the coffee machine. Rightfully so: coffee’s high dose of caffeine effectively ‘blocks’ the neurochemical adenosine that makes you feel sleepy. However, as a side effect, it also delays our sleep onset, reduces sleep quality, and shortens the total sleep duration.
Consequently, a 2000-study set out to compare coffee to its ‘light’ counterpart: (black) tea.
The study had 30 healthy adults (both men and women) drink black tea, black coffee, or water in equal amounts four times a day (morning, afternoon, evening, and late evening) over separate test days. Participants rotated through these drinks in a randomised order, with a six-day break between test days to reset.
They tested alertness, reaction time, and sleep quality using various methods, like reaction-time tests and questionnaires, to see how each drink affected performance and sleep.
The results on sleep were not so surprising. Because tea has less caffeine, it messes with sleep much less than coffee does. Drinking coffee—especially at higher doses—deteriorated participant’s sleep much more.
On focus and alertness, things got interesting. Within 30–90 minutes of drinking tea, participants scored better on a test measuring alertness compared to coffee when the caffeine content was matched. On reaction time, coffee drinkers responded only slightly faster than tea drinkers did.
Tea drinkers in the study had consistent levels of alertness throughout the day. Coffee, on the other hand, gave a quick boost but sometimes led to sharper drops later.
As such, the study concluded:
This study […] demonstrates that day-long tea consumption produces similar alerting effects to coffee, despite lower caffeine levels, but is less likely to disrupt sleep. (p.)
But how can this be? The authors argue that the benefits of tea on concentration might be attributed to its flavonoid content, which could enhance focus on their own.
What’s more: research indicates that these flavonoids may play a role in cognitive health, slowing down age-related cognitive decline. (See for example this recent systematic review by Godos & colleagues).
Tea offers a smoother, balanced boost compared to coffee’s intense jolt, keeping you alert without wrecking your sleep. For focus and better rest, tea might just be the smarter sip.
This ‘research says’-article is based on: Hindmarch, I., Rigney, U., Stanley, N., Quinlan, P., Rycroft, J., & Lane, J. (2000). A naturalistic investigation of the effects of day-long consumption of tea, coffee and water on alertness, sleep onset and sleep quality. Psychopharmacology, 149(3), 203–216. https://doi.org/10.1007/s002130000383
