How does caffeine affect sleep

However, during conditions of chronic caffeine intake, mice showed a deeper sleep compared to placebo Moreover, repeated caffeine intake enhances the sensitivity of adenosine binding 34 presumably due to upregulated adenosine receptors 26 , 27 , 28 or changes in the functions of adenosine receptor heteromers These neuronal alterations in the adenosinergic system might drive the commonly observed changes in the homeostatic sleep-wake regulation such as increased sleepiness when caffeine intake is suddenly ceased As reported previously, we also observed in the present study higher subjective sleepiness following caffeine withdrawal when compared to the placebo and caffeine conditions Thus, the reduction in sigma activity might reflect adenosinergic changes which already emerge 8 and 15 h after the last caffeine intake in the caffeine and withdrawal condition, respectively.

This reduction might reflect withdrawal symptoms which chronic consumers reverse daily by the first caffeine dose. Given the high prevalence of daily caffeine consumers in the society, these findings stress the importance to carefully control for prior caffeine intake when assessing sleep in order to exclude potential confounding by induced withdrawal symptoms which are only detectable in the microstructure of sleep.

Our study has some limitations which must be taken into careful consideration when interpreting the present findings. First, age moderates the effects of caffeine on sleep 11 , Thus, the present results cannot be generalized to other age groups such as to middle-aged consumers which are more vulnerable to the caffeine-induced effects on sleep 11 , Second, only a limited number of participants were studied.

However, a well-controlled study design was employed and power calculation on the basis of an earlier study 12 indicated a sufficient sample size.

In addition, a genetic variation of the ADORA2A genotype has been linked with caffeine sensitivity to the effects on sleep Thus, carriers of this genetic variance are more likely to curtail caffeine consumption and are consequently excluded from the present study leading to a selection bias. However, the focus of the present study was to investigate habitual caffeine consumers as they represent the majority of the worldwide population 2.

Fourth, to reduce variance in the data incurred by the influence of the menstrual cycle on sleep 39 and the interaction between caffeine metabolism and the use of oral contraceptives 40 , 41 , only male volunteers were included which clearly reduces the generalizability of the findings. In conclusion, we report evidence that daily daytime intake of caffeine and its cessation has no strong effect on sleep structure or subjective sleep quality.

However, the quantitative EEG analyses revealed reduced activity in the sigma range during both caffeine and withdrawal. These subtle alterations point to early signs of caffeine withdrawal in the homeostatic aspect of sleep-wake regulation which are already present as early as 8 h after the last caffeine intake. Thus, habitual caffeine consumers constantly expose themselves to a continuous change between presence and absence of the stimulant. Around the clock, their organisms dynamically adapt and react to daily presence and nightly abstinence.

Twenty male volunteers were recruited into the present study through online advertisements and flyers distributed in public areas. To ensure good health, volunteers were screened by self-report questionnaires and a medical examination conducted by a physician. To reduce variance in the data incurred by the effect of menstrual cycle on sleep 39 and the interaction between caffeine metabolism and the use of oral contraceptives 40 , 41 , only male volunteers were studied.

A detailed description of the study sample can be found in Weibel et al. All volunteers signed a written informed consent and received financial compensation for study participation. We employed a double-blind, randomized, crossover study including a caffeine, a withdrawal, and a placebo condition.

Volunteers were allocated to the order of the three conditions based on pseudo-randomization, for more details see Weibel et al. This regimen was applied based on a previous study investigating tolerance to the effects of caffeine and caffeine cessation To enhance caffeine withdrawal in the withdrawal condition, treatment was abruptly switched from caffeine to placebo on day nine of the protocol min after wake-up, 15 h before sleep recording.

Illustration of the study design. Each condition started with an ambulatory part of 9 days and was followed by a laboratory part of 43 h. After 9 days of continuous treatment, we recorded 8 h of polysomnography PSG , indicated as arrows, during nighttime sleep under controlled laboratory conditions.

During intake of caffeine i. The duration of the ambulatory part was set for 9 days based on the maximum duration of withdrawal symptoms 17 and thus, to avoid carry-over effects from the previous condition. Furthermore, volunteers were requested to refrain from caffeinated beverages and food e. Caffeine abstinence and compliance to the treatment requirements were checked by caffeine levels from the daily collection of fingertip sweat of which results are reported in the supplemental material of Weibel et al.

On day nine, volunteers admitted to the laboratory at 5. Upon arrival, a urinary drug screen AccuBioTech Co. Electrodes for the PSG were fitted and salivary caffeine levels collected.

To reduce potential masking effects on our outcome variables, we standardized food intake, light exposure, and posture changes throughout the laboratory part. Volunteers were asked to maintain a semi-recumbent position during wakefulness, except for restroom breaks.

In addition, volunteers received standardized meals in regular intervals. Social interactions were restricted to team members and no time-of-day cues were provided throughout the in-lab protocol. To characterize individual caffeine levels during nighttime sleep, we report salivary caffeine levels assessed 3 h prior to the scheduled sleep episode and 5 min after wake-up.

Liquid chromatography coupled to tandem mass spectrometry was used to analyze the levels of caffeine. One dataset in the withdrawal condition was lost.

Subjective sleep quality was assessed 10 min upon scheduled wake-up time with a paper and pencil version of the LSEQ Grass gold cup electrodes were applied according to the international 10—20 system including two electrooculographic, two electromyographic, two electrocardiographic, and six electroencephalographic derivations F3, F4, C3, C4, O1, O2. Channels were referenced online against the linked mastoids A1, A2. Signals were recorded with a sampling rate of Hz and a notch filter was online applied at 50 Hz.

Each epoch of 30 s of the recorded PSG data was visually scored according to standard criteria 47 by three trained team members blind to the condition. SWS was additionally classified into stage 3 and 4 based on Rechtschaffen and Kales Sleep latency to stage 1 and 2 was calculated as minutes to the first occurrence of the corresponding sleep stage following lights off.

REM sleep latency was calculated as minutes to the first occurrence of REM sleep following sleep onset. NREM sleep was calculated as sum of sleep stages 2, 3 and 4.

Artifacts were manually removed based on visual inspection, and data were log-transformed prior to spectral analyses. Withdrawal symptoms were first assessed 35 min after wake-up and subsequently prior to each treatment administration with the self-rating CWSQ Prior to analyses, eight items have been reversed scored as they were positively worded e. To assess caffeine withdrawal, we first calculated a sum score comprising all 23 items of the caffeine withdrawal questionnaire.

Missing responses to single items were replaced by the median response of each condition over all volunteers in the respective time of assessment. In a next step, we calculated relative withdrawal symptoms in the caffeine and withdrawal condition i. The data of one volunteer was lost due to technical difficulties. Analyses were performed with the statistical package SAS version 9. Post-hoc comparisons were adjusted for multiple comparisons by applying the Tukey-Kramer method.

Fredholm, B. Actions of caffeine in the brain with special reference to factors that contribute to its widespread use. Heckman, M. Caffeine 1,3,7-trimethylxanthine in foods: a comprehensive review on consumption, functionality, safety, and regulatory matters.

Food Sci. Snel, J. Effects of caffeine on sleep and cognition. Brain Res. Article PubMed Google Scholar. Martyn, D. Temporal patterns of caffeine intake in the United States. These symptoms include:. Some retailers sell pure caffeine powder in bulk.

It is marketed as a dietary supplement. Parents need to be aware that many teens and young adults take it for an energy boost. Others consume caffeine powder in an attempt to enhance performance or lose weight. Caffeine powder is highly potent, and a safe serving size is extremely small.

It is nearly impossible to measure caffeine powder accurately in the home. As a result the risk of an accidental, lethal overdose is high. Caffeine has both positive and negative attributes. It can be very effective for improving your concentration, alertness and energy.

But these effects can be brief if you consume high doses of caffeine on a daily basis. Caffeine also can have a negative effect on your sleep. It can reduce the quantity and quality of your sleep. These effects can occur even when you are unaware of them. Like most substances, you should use caffeine in moderation. These are some general guidelines for you to follow:.

Caffeine levels vary widely from one product to another. In particular, the caffeine content of coffee can be very unpredictable. Scientists at the University of Florida bought a oz cup of the same type of coffee from one coffee shop for six straight days. They analyzed each cup of coffee to determine how much caffeine it contained.

They found a wide range of caffeine levels in the six cups of coffee. Every morning, you walk downstairs and head for that glistening coffee pot to make a steaming hot cup of joe. However good that first cup of morning coffee tastes, the feeling that comes from drinking coffee can be even more enticing. Caffeine is a stimulant with powerful physical and mental effects. Once ingested, caffeine takes effect within 15 to 20 minutes, and half of that caffeine can remain in your system for can last for six or more hours.

It is the amount of time it takes caffeine to work its way out of your system. This can vary from four to six hours, or more, but seems to average around 5. How would that look in real time? For instance, a mid-afternoon cup of coffee may interfere with your ability to fall asleep many hours later. Your individual sleep-wake routine also will play a role in the timing of your caffeine consumption.

Even though caffeine can marginally boost performance, it is no substitute for a restful, restorative night of sleep.

It is also proposed that the effectiveness of caffeine varies depending on the dose and the state of the individual. For example, the arousing effects of caffeine may benefit someone who feels foggy and tired. For someone who is already alert and aroused, however, caffeine may cause over-arousal and lead to anxiety, restlessness, and dependency. While there are short-term performance benefits to caffeine consumption, overuse can lead to insomnia symptoms or worsen pre-existing insomnia.

Consuming caffeine to stay awake at night may lead to sleeplessness, anxiety, frequent nighttime awakenings, and overall poorer sleep quality. In addition, caffeine from sodas has been linked to increased severity of sleep-disordered breathing SDB , which is the primary characteristic of Obstructive Sleep Apnea OSA. Notably, this association was only found with caffeinated sodas, but not with coffee or tea, although it is unclear why.

Regardless, those who suffer from sleep-disordered breathing may not know about their sleep disruption and find themselves attributing excessive daytime sleepiness to other causes. If you struggle with sleepiness during the day, it might be helpful to reevaluate your caffeine consumption, especially from sodas. It may seem counterintuitive, but some people feel like caffeine makes them tired instead of more alert.

The disruptive effects of regular caffeine use on sleep can create a vicious cycle. Caffeine use causes sleep deprivation, and sleep deprivation causes sleepiness the subsequent day, which in turn causes an increased need to consume more caffeine in order to cope with the sleepiness.

Even with increased caffeine consumption, sleep deprivation catches up. People may be especially aware of their long-term sleep loss after they consume caffeine because they do not experience the pick-me-up they expected, and instead feel sleepy. Sleepiness can also be a symptom of abstinence from caffeine, which is why regular caffeine users may feel overly sleepy in the morning when they have gone all night without caffeine. Since caffeine can be both beneficial and harmful depending on the dose, it is important to find a level of consumption that is healthy for you.

The Food and Drug Administration FDA recommendation for safe daily caffeine consumption sits around mg, or cups of coffee per day. A large cup of coffee can have up to mg of caffeine content which is more than the daily recommended caffeine content. Since there can be a lot of variation in the way people respond to and metabolize caffeine, talk to your doctor if you are unsure if your caffeine consumption is recommended.

The recommended cut-off time for caffeine use is a minimum of six hours before bedtime. For example, if you typically go to bed at 10pm, avoiding caffeine after 4pm can help minimize sleep problems.

If you find the six-hour recommendation is not enough, make note of the times you consume caffeine and how you sleep the subsequent night. You may find you sleep better with a longer period of caffeine abstinence before bed. Are you struggling with insomnia, headaches, or anxiety during the day? This could be a sign of caffeine overuse and dependence. Troubles during the night, like frequent awakenings, inability to fall asleep, and nighttime anxiety may also be a sign caffeine is interfering with your sleep In that case, it may be time to put down the coffee and catch up on some much-needed rest.

Monitoring your caffeine use is just one way you can help yourself get regular, restorative sleep. Other lifestyle choices, like a healthy diet and exercise regimen , can contribute to healthy sleep. Good sleep hygiene is comprised of all the habits and routines that optimize your sleep quality:. Danielle writes in-depth articles about sleep solutions and holds a psychology degree from the University of British Columbia.

She specializes in helping parents establish healthy sleep habits for children. Terminology about sleep can be confusing. Our sleep dictionary clearly explains common sleep terms so that you can better understand…. This guide to diabetes and sleep discusses common sleep problems, consequences of sleep deprivation, and the link between type 2….

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