Some individuals may find that caffeine intake is associated with a reduced sleep quality and increased daytime sleepiness3,5, although additional research in middle-aged adults has suggested variable results4.
Research suggests that feeling tired in the morning can lead to high caffeine consumption to improve alertness and performance. However, this in turn may be associated with impaired subsequent sleep patterns, called a “coffee cycle”5.
A 2020 meta-analysis also concluded that caffeine may have a significant effect on performance after sleep loss, through positive impacts on physical and cognitive functioning. The authors suggested that dose variability may explain some of the intra-individual differences observed2. However, this effect is not universal, it has been proposed that after a period of overnight abstinence, the improvements associated with caffeine consumption may simply be associated with the reversal of caffeine withdrawal5.
A 2023 meta-analysis suggested that caffeine consumption may reduce total sleep time by 45 min and sleep efficiency by 7%. Additionally for some, the duration and proportion of light sleep increased with caffeine intake, whereas the duration and proportion of deep sleep decreased with caffeine intake14. A 2025 systematic review examined the relationship between long-term caffeine consumption and subjective sleep quality, defined as satisfaction with sleep based on personal perception, and found the relationship to be unclear. Variability in study quality, data, and assessment methods lead to limited statistically significant associations; with individual differences and study heterogeneity identified as key issues15, highlighting the need for standardised tools and methodologies in future research on this topic.
Across studies, the most commonly reported effects of caffeine on sleep consist of prolonged sleep latency (the time taken to fall asleep), shorter total sleep time, worsened perceived sleep quality, increased light sleep and shortened deep sleep time. Caffeine was also associated with more frequent awakenings, however Rapid Eye Movement (REM) sleep was less affected3.
However, a 2026 cross-sectional study of 30,154 adults aged 50–64 years suggested very low associations between different degrees of coffee consumption and estimated patterns of sleep habits or perceived daytime sleepiness. The authors suggested that coffee may be less impactful on sleep habits than previously thought, or that other mechanisms may play a role4. Counterintuitively, all sleep factors but sleep time and frequency of snoring indicated better sleep with higher coffee consumption4. Further research is required to investigate these findings4.
Variability in the effect of caffeine on sleep
Human sensitivity to the effects of caffeine on sleep is variable and its exact basis is still debated. A 2016 systematic review on coffee, caffeine and sleep concluded that individuals respond differently to caffeine based on a variety of factors, including age, sensitivity levels, regular coffee and caffeine intake, time of consumption, and genetic variability3.
It may be possible that people learn to regulate consumption to fit their individual patterns of response. A European study of 2,202 participants gathered data on sleep characteristics and the use of pharmacologically active compounds, including caffeine. Researchers found that caffeine consumption did not predict difficulties inducing sleep or other sleep disturbances when age, gender, smoking, and seasonal variations were controlled for5.
More information on how individuals may react differently to caffeine can also be found here.
Genetic variability
The research in this area is limited, with differing results. A 2019 study noted Adenosine A2a receptor gene (ADORA2A) genetic variations related to the duration of nocturnal sleep only in low caffeine consumers (< 50mg per day). The authors suggested that in moderate caffeine consumers (51–300mg per day) nocturnal sleep decreases irrespective of genetic variants and that genetic variants of ADORA2A seem not to influence the total sleep time above this moderate level16. A 2026 cross-sectional study examining different degrees of coffee consumption, including analyses of relevant genetic variants, found only very low associations with estimated patterns of sleep habits or perceived daytime sleepiness. The authors cautioned that middle-aged coffee consumers in the study may have been less susceptible to the effects of caffeine, potentially masking the role of ADORA2A4.
Age and caffeine sensitivity
Only a few studies have evaluated the age-related effects of caffeine on sleep, and confounding factors are often present. Some research suggests that older adults may be more sensitive to the effects of caffeine. However, caffeine exposure may vary as a function of body weight. For example, older adults tend to consume the same amount of caffeine as younger adults, but typically weigh less. Older adults may also self-limit the amount of caffeine they consume due to perceived sleep problems3.
Results from a 2025 review suggest that subgroup analyses showed that caffeine reduced total sleep time in both young and middle-aged adults. In the young group, caffeine also reduced sleep efficiency and prolonged sleep onset latency. Therefore, the authors reinforced the need for age- and dose-specific public health guidance to minimise caffeine-related sleep disturbances and to protect restorative sleep across the lifespan17.
Habitual intake of caffeine
Research suggests that the effects of caffeine are less marked in those who regularly drink coffee when compared to occasional coffee drinkers18. Results from a 2015 research survey concluded that sleep quality was poorer in those who perceived themselves to be dependent upon caffeine, particularly amongst females. Caffeine dependence was associated with poorer sleep quality, increased daytime dysfunction, and increased levels of night-time disturbance19.
Time of consumption
Caffeine consumed closer to sleep time has the greatest potential for sleep disruption, although there are only limited studies that assess the timing of caffeine administration. Evening consumption of 200mg caffeine is suggested to be linked with an increased sleep latency (by 7 min), reduced sleep efficiency (by 5%), and decreased sleep duration and stage-2 sleep (by 28 min) in older and younger adults3.
A 2025 randomised control trial concluded that 100 mg of caffeine can be consumed up to 4 hours prior to bedtime, but 400 mg of caffeine may negatively impact sleep when consumed in one go within 12 hours of bedtime, with the adverse influence on sleep increasing the closer consumption occurs to bedtime20.
The effects of caffeine abstinence
Some researchers have suggested that abstaining from caffeine for a whole day could improve sleep quality and could be recommended by health practitioners when giving sleep hygiene advice21. However, the effect may be complicated by the fact that caffeine consumption may be a response to fatigue as well as a cause of it. Some have suggested that following overnight avoidance of caffeine, improvements in performance the next day may simply be due to the reversal of the impact of caffeine withdrawal5.
