Effects of daily caffeine intake on nighttime sleep in young adult males.

Weibel, J., Lin, YS., Landolt, HP. etal. Effects of daily caffeine intake on nocturnal sleep in young adult men. SCI Rep 11, 4668 (2021). https://doi.org/10.1038/s41598-021-84088-x

Commentary

It is generally known that ingesting caffeine can affect sleep, but if it is taken suddenly, especially in the evening, it may delay the onset of sleep and decrease the intensity of sleep. However, it is not known if these effects are altered for caffeine that is consumed continuously during the day.

This study will investigate the sleep of 20 young male habitual caffeine consumers during a double-blind randomized crossover trial involving three 10-day conditions of caffeine (3 x 150 mg caffeine per day), withdrawal (3 x 150 mg caffeine per day).

After a 9-day intervention, electroencephalographic (EEG)-derived sleep structure and intensity were recorded during scheduled 8-hour nocturnal sleep episodes beginning 8 hours (caffeine state) and 15 hours (withdrawal state) after the last caffeine intake. At the scheduled waking time, subjective sleep quality and caffeine withdrawal symptoms were assessed. Total sleep time, sleep onset latency, sleep architecture, and subjective sleep quality obtained from the polysomnogram did not differ between placebo, caffeine, and withdrawal symptoms.

Despite these results, EEG power density at sigma frequencies (12-16 Hz) during non-REM sleep was reduced in both caffeine and withdrawal conditions when compared to placebo. These results indicate that daily caffeine intake in the morning and afternoon does not significantly impair the nocturnal sleep architecture or subjective sleep quality of healthy, good sleepers who regularly consume caffeine, and the reduction in EEG power density in the sigma range may represent an early sign of nocturnal withdrawal from the continued presence of daytime stimulants.