05 November 2014

Sleep deprivation in long mountain ultra trail running

Strangely, one thing I already now know that I will miss if I am only running shorter skyrunning and mountain trail ultramarathons next year is the absolute fatigue towards the end of the race due to not only the physical exhaustion, but also the sleep deprivation. I both dread and long for this feeling of having given everything and being on the limits for what both my body and mind tolerate. As I discussed in one of my recent posts the struggle to be in control in this stressful situation is something which clearly motivates me to race and it is something which has been found to motivate also mountaineers in long and strenuous alpine climbs. It is also fascinating how quickly at least I tend to forget how difficult and dangerous some situations are and it is almost surrealistic to see how I and my teammate Otto looked before we started Petite Trotte à Léon (PTL), half way in Morgex after approximately 100 miles and 15000 D+ meters, and immediately after the race. It is clear that the deterioration was rather severe towards the end of the race, we look surprisingly fresh in Morgex, and that is largely due to the sleep deprivation I think.
Pictures by Carole Pipolo before, during and after PTL 2014 of Otto and myself in the Swedish team "Living the Dream".
The sleep deprivation I felt towards the end of both Tor des Géants (TDG) in 2013 and Petite Trotte à Léon (PTL) in 2014 really forced me to struggle to be in control of my body and my faculties. In TDG I got strong déjà vu experiences the last two days of the race, I had a very strong almost psychotic paranoid experience during the last night of the race when I firmly believed that I would be forced to abandon the race if I was overtaken by runner’s behind me lower in the valley, and the last morning of the race just hours before finishing I literally struggled to not fall asleep during each step on the single-track between the Bonatti and Bertone refugios (mountain huts) and fall to my death down in the beautiful Val Ferret. Nevertheless, thinking back I did not completely lose control, which I clearly did the last night of PTL. Despite caffeine tablets, load music and interesting conversation with my teammate Otto I was more sleeping than awake when ascending Col Tricot, the last major climb of the race, and I was lucky that the climb was traversing a valley on a large fire-road giving me space to stumble as I was losing my balance. I woke up at the top of the climb, only to find myself in a real nightmare on the very last descent from Bellevue to Les Houches through the dark forest of Arandellys. I still do not know how I survived this descent without falling on the wet slippery roots in the dark. I also had quite strong visual hallucinations with rocks and trees turning into various faces this last night, something I did not experience at all during TDG. In contrast, I had just one déjà vu experience during PTL and that came one of the first nights of the race and it is strange that I reacted that differently in both races. Reading race reports from TDG, PTL and other long mountain ultramarathons and discussing with other runners it is clear that one person can react quite differently on sleep deprivation at different races. That different persons react differently is perhaps not so strange and one of my favorite YouTube films is Nickademus Hollon’s compilation of “Tor des Geants 2014 Hallucination Stories”, which clearly illustrates how different the reactions can be. My favorite story is the one 8 minute into the film where one runner describes how he during the race actually thought he was Barack Obama.
As clearly sleep deprivation is a major factor in longer mountain ultramarathons it is with great interest I read a new article by Hurdiel and colleagues about lack of sleep during the 100 mile (168 km) Ultra Trail du Mont Blanc in 2013 (Hurdiel et al “Combined effects of sleep deprivation and strenuous exercise on cognitive performances during The North Face® Ultra Trail du Mont Blanc® (UTMB®)” J Sport Sci 2014; Epub ahead of print). In the study, 17 finishers (16 males and 1 woman with a mean age of 43.4 ± 6.4 years and finish time of 36 h 02 min ± 7 h 18 min) and mean duration of sleep deprivation (between wake-up time on race day and finish time) of 46 h 38 min ± 5 h 20 min were tested with a wrist-worn triaxial actigraph to record sleep time and cognitive objective psychomotor vigilance performance was evaluated before and immediately after the race with simple 10-minutes serial response time tests. The actigraph data indicated 12 ± 17 min of rest during the race, comprising of 1.2 ± 1.4 naps. Naps lasted 9 ± 5 min (range of 4 to 22 min) and nine runners did not sleep at all. Analysis of sleep data revealed that rest as a function of time in the race fit a (second order) quadratic regression model, with longer time in the race not surprisingly correlating with longer sleep duration in the race. Eight of the runners (47%) experienced clinical symptoms of sleep deprivation including four runners (24%) with visual hallucinations, five runners (29%) with difficulties keeping their eyes open while running and three runners (18%) with loss of balance during the race. The cognitive objective psychomotor vigilance performance was impaired after the race with a mean response time of 86% of that before the race and the number of errors of commission was statistically significant greater after the race, although there was a very large inter-individual variation. Most interestingly, there was no correlation between cognitive performance and either amount of rest obtained or time into the race. It was therefore not possible to predict just by analyzing the duration of the sleep deprivation who will develop cognitive impairments, suggesting that there are personal factors that affect individual performance in the absence of sleep, and the authors conclude that these factors will require further research.
I think it would be very interesting to study sleep deprivation in the even longer continuous mountain ultramarathons like TDG, PTL or the new US races Tahoe 200 and Bigfoot 200 and how this could be affected by other factors like caffeine intake and race strategy. In retrospect it is absolutely clear that I probably would have gained by changing the race strategy and slept for one hour the last night of both TDG and PTL before the sleep deprivation became too severe, but on the other hand then I would not have tested my limits to the same extent.