It is also proposed that the effectiveness of caffeine varies depending on the dose and the state of the individual. Even though caffeine can marginally boost performance, it is no substitute for a restful, restorative night of sleep.

While caffeine can boost cognitive function in the severely fatigued, it cannot permanently ward off sleep or fix the effects of long-term sleep loss. Most people drink coffee in the morning to help them wake up, but caffeine consumed at night can cause more harm than good. Can Caffeine Keep Me Awake?Ĭaffeine can cause a burst of energy as it stimulates the central nervous system. If you have difficulty sleeping, consider limiting any caffeine intake six hours before bed. In addition, study participants reported sleeping problems when consuming caffeine 0-3 hours before bed, but they did not realize their sleep was also disrupted when consuming caffeine six hours before bed. One study examined the effects of caffeine intake zero, three, and six hours before bedtime, and found that even caffeine consumed six hours before bed could reduce sleep time by one hour. Caffeine-interrupted sleep can lead to sleep deprivation the following day, which is characterized by fatigue and problems with learning, memory, problem-solving, and emotion regulation. Caffeine notably reduces the time of slow-wave sleep, which is the stage of deep, restful sleep that leaves us feeling refreshed and alert in the morning. Older adults may also be more susceptible to caffeine-induced sleep troubles. If you are pregnant or breastfeeding and concerned about your caffeine intake, talk to your health care provider about what steps you should take to ensure optimum health for you and your baby.Ĭaffeine can impact the onset of sleep and reduce sleep time, efficiency, and satisfaction levels. A trace amount of caffeine can also be found in breast milk. It is recommended that those who are pregnant or breastfeeding should avoid coffee, or limit intake to 16 ounces or less per day (about two cups of coffee).ĭuring pregnancy, caffeine can be passed to the baby through the placenta. By contrast, pregnant women experience slower caffeine metabolism. Nicotine use can reduce the half-life of caffeine by up to 50%, so frequent smokers process through caffeine much quicker, with a half-life as short as two hours. Some factors can slow or speed up the metabolism of caffeine. As a result, the six-hour half-life of a caffeinated beverage you consume in the afternoon could keep you up at night. The half-life means the time that your body has metabolized, or processed through, half the caffeine you consumed. The effects of caffeine are measured by its half-life, which typically ranges from 4-6 hours. The buildup of adenosine contributes to this process, and caffeine’s interference with this process may explain its impact on circadian rhythm. They are held in check by the external cycle of day and night, and by internal cellular processes. Circadian rhythms are physiological patterns, like our sleep-wake cycle, that operate on a 24-hour clock. Research has also shown that caffeine interferes with circadian melatonin rhythms, delaying the onset of sleep if consumed close to bedtime. When caffeine blocks this process, we remain alert and vigilant. The more it builds up, the sleepier we become. Normally, adenosine builds up in the brain the longer we’re awake. Adenosine is a sleep-promoting chemical that is produced in the brain during our waking hours. Inside the brain, caffeine blocks adenosine receptors.

After being absorbed, caffeine is efficiently distributed throughout the whole body, and it crosses the blood-brain barrier. The maximum effects of caffeine usually occur between 30-60 minutes within consumption, although this timing can vary widely among individuals. When we consume caffeinated drinks and foods, our stomachs and small intestines quickly absorb the caffeine.

Coffee makes me sleepy