New Study Finds Coffee Lovers Sleep Less, But Walk More

Drinking a minimum of one cup of coffee daily may lead to increased physical activity, but also decreased sleep and a heightened risk of a specific heart palpitation.

A recent small-scale study published in The New England Journal of Medicine presented these results regarding daily coffee consumption, indicating both advantages and disadvantages to the drink of choice for many. 

Results of the Study on Coffee Consumption

Dr. Gregory Marcus, the study’s principal investigator and a cardiologist and professor of medicine at the University of California, San Francisco, explained that the effects of coffee consumption on health are more complex than previously thought. Most research in this area has been observational, which can be heavily influenced by other factors. To address these limitations, the researchers conducted a randomised interventional trial.

To better understand the immediate health impacts of coffee, the researchers enlisted 100 healthy adults with an average age of 39 from the San Francisco area. Participants were given Fitbits to monitor their steps and sleep, continuous blood glucose monitors, and electrocardiogram devices to record their heart rhythms. Each individual was randomly instructed to drink coffee at their discretion for two days, followed by abstaining for two days. The participants repeated this process for two weeks.

The study found that participants took an average of 1,058 additional steps on days they consumed coffee compared to abstention days. However, sleep quality suffered, with participants experiencing a reduction of 36 minutes on average. The findings also suggested that increased coffee intake led to heightened physical activity and further sleep reduction.

Does Drinking Coffee Have Negative Health Effects?

Dr. Marcus suggests that coffee consumption may boost motivation for exercise or improve performance during physical activity. However, he warns against extrapolating these results to consuming energy drinks or high doses of caffeine for enhancing workouts, as excessive amounts can lead to adverse effects.

The study found that coffee consumption was linked to reduced sleep, which may not be surprising. However, the potential genetic aspect of this finding is noteworthy. The researchers collected DNA samples from participants and discovered that individuals with genetic variants associated with slower caffeine metabolism experienced greater sleep reduction when consuming coffee. Conversely, those with genetic variants associated with faster caffeine metabolism had more premature ventricular contractions (PVCs).

These results imply that a personalised approach to coffee consumption might be the best way to determine its health effects, as suggested by the study.

Peter Kistler, who is head of electrophysiology at the Alfred Hospital in Melbourne, Australia, offers a different perspective on the reduced sleep finding, stating that coffee is the most prevalent “drug” for cognitive enhancement. He argues that coffee drinkers are less tired, which is not necessarily a negative consequence.

As for the connection between coffee intake and PVCs, Marcus explains that caffeine has active metabolites like aminophylline, which is found in asthma medications and can induce arrhythmias at high doses. Furthermore, he adds that coffee consumption can increase activity in the sympathetic nervous system (the adrenaline-fueled side), potentially leading to PVCs.

Why is Coffee so Addictive? 

Coffee’s addictive nature can largely be attributed to its primary active ingredient, caffeine. As a central nervous system stimulant, caffeine can temporarily ward off drowsiness and restore alertness, making it an appealing option for those seeking a quick energy boost. 

When consumed, caffeine blocks adenosine, a neurotransmitter that promotes sleep and relaxation, leading to increased dopamine levels, which create a sense of pleasure and reward. Over time, regular coffee drinkers may develop a dependency on caffeine, as their brains adjust to its effects and require higher doses to achieve the desired stimulation. 

This can result in withdrawal symptoms, such as headaches, fatigue, and irritability when caffeine levels drop, further reinforcing the cycle of consumption and addiction. However, it’s important to note that individual susceptibility to caffeine addiction varies, and not all coffee drinkers will experience the same degree of dependence.

Too much of a Good Thing?

Drinking coffee in moderation can offer a range of benefits, from increased physical activity and motivation to cognitive enhancement. However, it’s important to remember that moderation is key. 

It’s recommended that adults consume no more than 400 milligrams of caffeine per day, roughly equivalent to four cups of brewed coffee. For those who are particularly sensitive to caffeine, it’s best to limit consumption even further. Ultimately, striking a balance between the positive effects of coffee and its potential drawbacks is crucial for achieving optimal health and wellbeing.

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