| Peer-review |
Original research papers or systematic reviews published in peer-reviewed journals |
Non-peer reviewed papers, book chapters, reports, conference proceedings were excluded |
| Subjects |
Participants should be young (16–26 yrs. old inclusive), healthy, non-professional driver, non-shift worker, free from sleep disorders |
Papers with broader age range were excluded |
| Sleepiness |
Sleepiness was induced by sleep deprivation only. Sleepiness could be induced by any type of sleep deprivation including acute or chronic sleep loss, extended wake periods, early morning wakeups (sleep limitation), sleep fragmentations or sleep disturbances |
Studies examining other forms of sleepiness without any prior sleep loss (e.g. time-on task fatigue or usual daytime sleepiness) were excluded |
| Exposure (independent variable) |
Sleep deprivation was the main exposure (independent variable) |
Studies examining the effect of countermeasures for sleepiness (e.g. light, modafinil, caffeine, exercise, nap, alcohol, etc.) on sleep deprived subjects were excluded |
| Outcome measures (dependent variable) |
The primary outcome measures of interest should include driving performance outcomes, either driving simulator or on–road. Driving performance outcomes could be studied individually or along with other objective and subjective determinants of sleepiness |
|
| Publication date |
Published between 1 January 2004 and 30 December 2016 |
|
| Study design |
Any type of study design; all study designs such as Randomised Control Trials (RCTs), experiments, cross-sectional and observational studies were included |
|
| Publication language |
Papers published in English only |
Papers published in other languages were excluded |
