Study Title and Description
Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed.
Key Questions Addressed
|1||For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on behavior*?|
Primary Publication Information
|Title||Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed.|
|Author||C Drake,T Roehrs,J Shambroom,T Roth,|
Secondary Publication Information
There are currently no secondary publications defined for this study.
Extraction Form: Behavior - Design Details - INCLUDED Studies
No arms have been defined in this extraction form.
|Question... Follow Up||Answer||Follow-up Answer|
|What outcome is being evaluated in this paper?||Behavior|
|What is the objective of the study (as reported by the authors)?||Sleep hygiene recommendations are widely disseminated despite the fact that few systematic studies have investigated the empirical bases of sleep hygiene in the home environment. For example, studies have yet to investigate the relative effects of a given dose of caffeine administered at different times of day on subsequent sleep.|
|Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods)||Subjects Participants were recruited from the Detroit tri-county area through local advertisements. The study group comprised 12 healthy normal sleepers, as determined by a physical examination and clinical interview. Habitual caffeine consumption was based on self-report. A total of 16 healthy day workers met initial screening criteria; data were not used from 4 subjects due to violation of the study protocol before the study blind was broken. This included 2 subjects who took caffeine on 4 consecutive nights without the required 1 night washout, one subject who did not go to bed at the scheduled times 3 of 4 nights, and one subject who did not comply with 8-h time in bed on study nights. Thus, 12 subjects completed the full protocol (6F, 6M; aged 19-48; mean age 29.3 ± 7.6). The mean baseline caffeine intake for the sample was 115 ± 169 mg/day of caffeine. All study procedures were approved by the institutional review board and informed consent was obtained from all participants. Individuals were compensated for their participation. Procedures The protocol was a randomized, double-blind, double dummy, placebo-controlled, balanced Latin Square treatment sequence design. For the experimental period, participants were instructed to maintain their normal sleep schedules, including a bedtime between 21:00 and 01:00, wake times between 06:00 and 09:00, time in bed of 6.5-9 h, and no habitual napping. Study protocol began following one week of baseline sleep diaries. Each subject completed 4 conditions/nights which consisted of 400 mg of caffeine taken in pill form at either 6, 3, or 0 hours prior to scheduled bedtime, with identical placebo given at each of the other times. Thus, subjects were instructed to take 3 pills each study day with one of the pills being caffeine and the other 2 placebo. On one of the days, all 3 pills were placebo. Conditions were presented in a Latin Square Design. Each caffeine condition was preceded by 1 washout night where subjects did not wear any sensors and did not take study drug. Thus, experimental nights occurred every other night during the protocol. However, sleep diary data were collected in the morning for all nights (experimental and washout). Subjects were given caffeine pills in an alarm activated pill case. Participants were required to maintain a fixed bedtime and wake time schedule based on sleep diaries throughout the protocol. Subjects were also given a sleep diary to complete each morning throughout the study. The pill case alarms were set according to the subjects’ habitual bedtime, and the alarm was designed to sound until the subject manually turned it off. In order to avoid any potential caffeine withdrawal effects subjects were allowed to use caffeine during the study. However, subjects were instructed to refrain from consuming any alcohol or caffeine after 16:00 on study days. The aim of the present study was to determine if caffeine administered at different times before bed in the home environment impacts measures of sleep disturbance compared to placebo. Thus, the impact of different caffeine administration times on sleep was measured using a standard sleep diary with items similar to those used for the consensus sleep diary.35 Sleep disturbance was also measured objectively using a widely available and previously validated in-home sleep monitor.36 The monitor was comprised of a headband unit containing dry fabric sensors that wirelessly transmitted a single-channel EEG signal obtained from the forehead to a bedside device for processing. Sleep parameters were computed in real-time by the device shown to have concordance with the current gold standard, polysomnography (PSG), as well as with actigraphy. Subjects were instructed to put on the wireless system headband immediately upon going to bed with the intent to go to sleep, and to keep the headband on all night long and place it back on its bedside device upon rising from bed in the morning. Adherence with the timing of the 3 daily pill administrations was done through the use of 3 timed pill alarm cases, which contained study drug for each night. Study drug intake was monitored by having subjects call in to a time stamped answering machine to verify that the study drug was taken at each predetermined time period (6 h prior, 3 h prior, and at bedtime). Data were analyzed using repeated-measures ANOVA with planned comparisons testing for differences between each caffeine administration time and placebo night. Data transformations were performed where appropriate when deviations from normality occurred. Significant omnibus results were followed by post hoc analyses to identify pairwise differences. A two-tailed α level of 0.05 was used for all statistical tests. A nonparametric Friedman two-way analysis of variance by ranks was used for variables which deviated from normality.|
|How many outcome-specific endpoints are evaluated?||1|
|What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately)||sleep|
|List additional health endpoints (separately).|
|List additional health endpoints (separately)|
|Notes||sleep measures included total sleep time, sleep efficiency, latency to persistent sleep, and wake time during sleep|
|What is the study design?||Controlled Trial|
|Randomized or Non-Randomized?||RCT|
|What were the diagnostics or methods used to measure the outcome?||Both|
|Optional: Name of Method or short description||sleep diary and headband unit with single-channel EEG signal|
|Caffeine (general)||Caffeine (general)|
|What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.)||placebo (0 mg caffeine) vs 400 mg caffeine|
|What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models. Copy from methods)||N/A|
|Provide a general description of results (as reported by the authors).||Caffeine had the most consistent effects on reducing total sleep time relative to placebo, with both administration at bedtime and 3 h prior to bedtime reaching statistical significance. Caffeine administered 6 h prior to bedtime reduced total sleep time by 41 min, which approached significance (p = 0.08). Significant effects were observed for sleep latency with caffeine taken 3 h before bed having the greatest effect relative to placebo. Although caffeine taken 6 h before bedtime more than doubled the reported time take to fall asleep, this effect did not reach statistical significance (p = 0.06). No significant effects were observed for WTDS, SE, or sleep quality. There were no significant differences between caffeine conditions for any of the sleep diary measures (Table 2). Evidence for the disruptive effects of caffeine was demonstrated for each of the sleep duration and continuity parameters. The different caffeine administration times (0, 3, or 6 h before bed) did not produce differential sleep disruption among the 3 active caffeine conditions. For TST, reductions in duration relative to placebo were significant at each of the caffeine administration time points, reducing TST between 1.1 to 1.2 hours. The 3-h condition significantly prolonged latency to persistent sleep (+17.2 min) relative to placebo. Latency to persistent sleep was similarly prolonged in the 0 and 6 h condition (+22.4 and +24.1 min, respectively), but neither reached statistical significance compared to placebo. The amount of wake time during sleep was also increased with all 3 caffeine administration times, reaching statistical significance for the 6 h (+8 min) and 3 h (+27.6 min) conditions. Sleep efficiency was reduced for each condition relative to placebo.|
|Did the authors perform a dose-response analysis (or trend/related analysis)?||No|
|What were the authors's observations re: trend analysis?|
|What were the author's conclusions?||The results of this study suggest that 400 mg of caffeine taken 0, 3, or even 6 hours prior to bedtime significantly disrupts sleep. Even at 6 hours, caffeine reduced sleep by more than 1 hour. This degree of sleep loss, if experienced over multiple nights, may have detrimental effects on daytime function. Caffeine-induced sleep disturbance was detected by both the self-report diary and objective sleep measures when taken at bedtime and 3 hours prior to bedtime, whereas only the objective measure detected differences when caffeine was taken 6 hours prior to bedtime.|
|What were the sources of funding?||The study was funded by an investigator initiated grant from Zeo Inc to Dr. Drake and performed at the Henry Ford Hospital Sleep Disorders & Research Center,Detroit,|
|What conflicts of interest were reported?||Dr. Drake has received funding from Merck, Teva, and Zeo. He has consulted for Teva. He has been a speaker for Teva, Purdue, and Jazz. Dr. Roehrs has been a speaker for Pfizer and has consulted for Sanofi Aventis. Mr. Shambroom has been a coauthor of publications appearing in the journal Sleep, supported by Zeo, Inc. He manages his own consulting business, Shambroom Associates, LLC, Framingham, MA. He has been in consulting relationships with Atentiv, Inc., Brainscope, Inc., SafeOp Surgical, Inc., and Cephalogics, Inc. He has been the VP Scientific Affairs for Zeo, Inc., from April 2007-April 2010. He no longer has financial interest in Zeo. Dr. Roth has served as a consultant for Abbott, Accadia, AstraZenca, Aventis, AVER, Bayer, BMS, Cypress, Ferrer, Glaxo Smith Kline, Impax, Intec, Jazz, Johnson and Johnson, Merck, Neurocrine. He has received research support from Cephalon, Merck, Transcept and has participated in speaking engagements for Purdue.|
|Does the exposure (dose) need to be standardized to the SR?||No|
|Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest).|
|List all the endpoint(s) followed by the dose (mg) which will be used in comparison to Nawrot. Characterize value as LOAEL/NOAEL, etc. if possible.||Sleep - LOAEL = 400 mg/day (sleep duration and continuity parameters / disturbances)|
|Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot.||single dose Effects seen at levels comparable to Nawrot et al. significant effects seen on subjective measures such as reduced total sleep time and increased sleep latency, no significant effects seen on wake time during sleep, sleep efficiency or sleep quality significant effects were also seen on objective measures: decreased total sleep time, amount of wake time during sleep, and prolonged latency to persistent sleep time|
|What is the importance of the study with respect to the adverseness of the outcome?||Important|
No baseline characteristics have been defined for this extraction form.
Results & Comparisons
No Results found.
|Arm or Total||Title||Description||Comments|
No quality dimensions were specified.
No quality rating data was found.