►Table 2.

Postive Effects of Sleep Extension.

Study	Population/Activity	Sleep Extension	Effect
Gillberg et al. 1996 [48]	Healthy volunteers	Midday ½ h nap following night of sleep deprivation (4 h total sleep)	Nap after restricted sleep brought performance on psychomotor vigilance tasks back to baseline; alertness improved, sleepiness decreased
Kamdar et al. 2004 [50]	Healthy college students	Sleep as much as possible/night over 7 nights (~2 h more sleep/night, from ~7 to 9 h)	Reaction time improved; daytime alertness, vigor, mood improved; fatigue decreased
Hayashi et al. 2005 [49]	Healthy university students	Midday nap following sleep deprivation (1.5 h less total sleep)	Alertness and performance on psychomotor vigilance tasks improved after nap, moreso with stage 2 sleep vs. stage 1
Brooks and Lack 2006 [47]	Healthy young adults	Afternoon nap following night of sleep deprivation (5 h total sleep)	Nap improved cognitive performance tasks, sleepiness, fatigue, vigor, alertness
Waterhouse et al. 2007 [43]	Healthy males	Midday ½ h nap or sit quietly following night of sleep deprivation (4 h total sleep)	Reaction time accuracy improved, 2 m & 20 m sprint times improved; alertness & short-term memory improved; sleepiness decreased
Mah 2008 [45]	Men’s and women’s collegiate swimming teams	Increase to minimum 10 h in bed/night over 5–7 weeks (~2 h more sleep/night)	15 m sprint swim improved, faster reaction times off the blocks, improved turn times, increased kick strokes; daytime sleepiness decreased mood & vigor improved, fatigue decreased
Mah et al. 2011 [42]	Men’s collegiate varsity basketball team	Increase to minimum 10 h in bed/night over 5–7 weeks (~2 h more sleep/night)	Half-court & full-court sprints improved, shooting accuracy improved (free throw and 3-point field goal percentage 9–9.2 %); vigor & mood improved; sleepiness & fatigue decreased
Schwartz and Simon 2015 [44]	Collegiate varsity tennis players	Increase to at least 9 h sleep/night over 1 week (~2 h more sleep/night)	Tennis serve accuracy improved (35.7 % to 41.8 %), sleepiness levels (Epworth & Stanford Scales) decreased
Arnal et al. 2016 [46]	Healthy men in 30’s with normal BMI	Increase time in bed by 1.6 h (habitual vs. extended time in bed 8.2→9.8 h) prior to 1 night of total sleep deprivation	Time to exhaustion during motor performance tasks (sustained muscle contraction) increased with sleep extension compared to habitual sleep at baseline by 3.9 % (prior to sleep deprivation). After a night of total sleep deprivation, time to exhaustion in sleep extension group doubled (8.1 %) compared to habitual sleep. There were no differences in voluntary muscle activation; likely effect is partially due to reduced rate of perceived exertion
O’Donnell and Driller 2017 [52]	Elite female netball athletes	Sleep monitoring pre-post a sleep hygiene education session by a specialist in sleep research and athletic recovery	Sleep hygiene education (presentations on sleep physiology, sleep hygiene practical tips, importance of sleep for athletes, and athlete Q&A) resulted in significant improvement in total sleep time, wake variance and wake episode duration.
Van Ryswyk et al. 2017 [51]	Australian Football League male athletes	Education session explaining normal sleep needs, how to improve sleep duration and quality, ongoing feedback	After a 6-week sleep optimization program, there were increases in total sleep time, sleep efficiency, vigor scores, and decrease in fatigue levels