Coffee shortens sleep but makes it deeper: new research data.

Impact of coffee on sleep quality

According to ТСН: Research has shown that daily consumption of four or more cups of coffee reduces the duration of night sleep but makes it much deeper.

Scientists from Zurich analyzed data from nearly half a million participants and the results of overnight polysomnographies of 1702 individuals to conduct their studies.

To eliminate the influence of other factors such as stress, fatigue, or lifestyle, researchers applied Mendelian randomization. This allows studying genetic characteristics of caffeine metabolism as a natural experiment. The results showed that consumers of four or more cups of coffee sleep on average 11–13 minutes less and sometimes even up to half an hour or more.

At the same time, the electrical activity of the brain indicated an increase in delta waves — the stages of sleep that are most restorative.

According to the authors, the body likely compensates for sleep deprivation by making deep sleep more intense.

Researchers point out that this does not mean that coffee positively affects sleep quality since the brain adapts to constant stimulation. However, the limits of such compensation remain unknown. In the future, scientists plan to investigate whether long-term caffeine consumption can alter sleep structure.

These findings call into question the conventional understanding of the impact of coffee on rest. Although the beverage may lead to deeper sleep, its excessive consumption may raise concerns about overall sleep quality. Further research may help understand how to properly consume caffeine to maintain healthy sleep.