A large Swedish study, published in the journal PLOS ONE, analyzed data from 25,381 people between the ages of 50 and 64.
The participants are part of the Swedish health survey, the Swedish Cardiopulmonary Bioimage Study (SCAPIS).
Among other things, they were asked about their coffee consumption using food frequency questionnaires.
The results showed that most participants drank coffee daily and generally reported good sleep quality. Only about 16 percent experienced pronounced daytime sleepiness.
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The body adapts
The analyses revealed only very weak statistical associations between coffee consumption and sleep problems.
According to the researchers, one possible explanation is that the body adapts to caffeine over time.
Changes in the brain can reduce the stimulating effect in people who drink coffee regularly.
This may help explain why habitual coffee drinkers do not experience the same sleep disturbances as people who consume caffeine only rarely.
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Genes play a role
Caffeine affects the central nervous system by blocking adenosine receptors, which normally help regulate sleep and wakefulness.
Previous genetic studies have shown that people break down caffeine at different rates.
Variations in genes linked to the cytochrome P450 system can influence how quickly caffeine is metabolized in the body.
In the SCAPIS study, genetic analyses were also used to verify participants’ reported coffee consumption.
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Among other findings, the researchers identified 66 genetic variations associated with coffee consumption.
Several factors affect sleep
The researchers emphasize that other factors also play a role in sleep quality.
Age, sex, BMI, stress level, physical activity, and smoking were among the factors included in the analyses.
Overall, the results suggest that coffee alone has only a limited impact on sleep among middle-aged adults.
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Sources: News-Medical, and PLOS ONE.
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