Sleep is more sensitive to high doses of caffeine in the middle years of life.
Level 2 - randomized trial
Individual double-blind randomized crossover trial
PubMed 25759402 · doi:10.1177/0269881115575535
What was done
Double-blind crossover study evaluating the effects of 200 mg and 400 mg of caffeine versus placebo on sleep architecture measured via polysomnography in 22 young adults (23.5 ± 1.9 years) and 24 middle-aged adults (51.7 ± 11.5 years).
What was found
Compared to placebo, caffeine increased sleep latency, shortened total sleep duration, and reduced sleep efficiency. At the 400 mg dose, these disruptions were more pronounced in middle-aged than young adults. High-dose caffeine increased absolute stage 1 sleep in young adults, whereas it decreased absolute stage 2 sleep in middle-aged adults. In both age groups, caffeine caused dose-dependent increases in relative stage 1 sleep and reductions in absolute and relative slow-wave sleep as well as absolute rapid eye movement sleep. No dose- or age-related modulation was observed in quantified electroencephalographic measures. Specific numerical values and effect sizes were not reported in the abstract.
Why it matters
Demonstrates that age-related vulnerability in sleep architecture makes middle-aged adults more susceptible to sleep disruption from high caffeine intake than younger individuals.
Limits
Small sample size (n = 46). The abstract omits exact numerical values, effect sizes, timing of caffeine administration, participants' habitual caffeine use, and daytime functional measures.
Cited by
- supports Consuming 200 mg of caffeine in the evening reduces deep slow-wave sleep by approximately 20%.