Title: Evidence of Disturbed Sleep and Increased Illness

30 31 Purpose: To examine whether i) objective markers of sleep quantity and quality are altered in 32 endurance athletes experiencing overreaching in response to an overload training program and ii) 33 whether potential reduced sleep quality would be accompanied with higher prevalence of upper 34 respiratory tract infections in this population. 35 Methods: Twenty seven trained male triathletes were randomly assigned to either overload (n=18) or 36 normal (CTL, n=9) training groups. Respective training programs included a 1-week moderate training 37 phase, followed by a 3-week period of overload or normal training, respectively and then a subsequent 38 2-week taper. Maximal aerobic power and oxygen uptake ( ̇O2max) from incremental cycle ergometry 39 were measured after each phase, whilst mood states and incidences of illness were determined from 40 questionnaires. Sleep was monitored every night of the 6 weeks using wristwatch actigraphy. 41 Results: Nine of the 18 overload training group subjects were diagnosed as functionally overreached 42 (F-OR) after the overload period, as based on declines in performance and ̇O2max with concomitant 43 high perceived fatigue (p<0.05), whilst the nine other overload subjects showed no decline in 44 performance (AF, p>0.05). There was a significant time × group interaction for sleep duration (SD), 45 sleep efficiency (SE) and immobile time (IT). Only the F-OR group demonstrated a decrease in these 46 three parameters (-5.4±5.3%, -2.1±2.0% and -5.7±5.0%, for SD, SE and IT, respectively, p<0.05), 47 which was reversed during the subsequent taper phase. Higher prevalence of upper respiratory tract 48 infections were also reported in F-OR (67%, 22%, 11% incidence rate, for F-OR, AF and CTL, 49 respectively). 50 Conclusion: This study confirms sleep disturbances and increased illness in endurance athletes who 51 present with symptoms of F-OR during periods of high volume training. 52 53