I slid twenty kilos onto each side of the bar and stepped under it. Sixty kilos with the bar. Ten reps at that weight is a warm-up for me, the set I do without thinking about it. I got to five and had to rack it. Nothing had gone wrong. I had slept badly, so I told myself that was the reason. Then it happened again the next week, and the week after. I am a physician, so my first move was to go looking for a number that would explain it. That search is what this episode is about, and it ended somewhere I did not expect. In this episode: What the largest review of sleep loss and physical performance actually found, and the reason it could not explain my own morning. The review left out exactly the situation most working adults are in, which is worth knowing before you read the headline. The 2003 study that changed how I think about my own judgment. People restricted to four or six hours in bed continued to see their performance decline for two straight weeks, while their sense of how tired they felt stopped changing. The researchers said they were largely unaware of it. The drive home I have told almost nobody about. My wife asleep in the passenger seat, an hour of fighting to stay awake, and the ten or twenty seconds I do not remember. Why I ordered a saliva cortisol test, and what a review of 190 studies says about whether cortisol can tell you anything about burnout. Adrenal fatigue, and what two endocrinologists found when they went through fifty-eight studies looking for it. You can now buy a cortisol curve as a stress score, and this is the part I want people to hear. The lab work behind those kits is real. Doctors use saliva cortisol to screen for Cushing's syndrome. The problem sits somewhere else entirely, and there is one question you can ask any company selling you a number. Psychological detachment, which is the ordinary business of your mind leaving work the way your body does, and what the workplace data shows about who manages it and who does not. The morning in our Berlin hallway when I could not put on my own socks, and what my wife said when I asked for help. Why I would write The Upward ARC differently now than I did in May 2025. Activate, Recover, Capacity works as a loop rather than a list, and the difference matters more than I realized when I first published it. The three kinds of capacity, and which one tends to go first. Five things to try, including the one I do that no study has ever tested, clearly labeled as such. If you have ever answered a bad stretch by adding more effort, this one is for you. --- Read the written edition, with all 10 references:https://www.andreheeg.com Under Load is the Sunday edition of The Upward ARC, written by Andre Heeg, MD, DDS. Evidence-led writing on executive health, longevity and performance under load, for people carrying real responsibility. Subscribe: https://www.andreheeg.com --- Studies and sources discussed in this episode are listed in full in the written edition. Key ones: Craven et al. (2022), Sports Medicine: effects of acute sleep loss on physical performanceVan Dongen et al. (2003), Sleep: the cumulative cost of additional wakefulnessWatson et al. (2015), Journal of Clinical Sleep Medicine: recommended amount of sleep for a healthy adult, AASM and Sleep Research Society consensusRothe et al. (2020), Neuroscience and Biobehavioral Reviews: cortisol in major depressive disorder and burnoutCadegiani and Kater (2016), BMC Endocrine Disorders: adrenal fatigue does not existNorton et al. (2023), Comprehensive Psychoneuroendocrinology: reliability of diurnal salivary cortisol metricsWendsche and Lohmann-Haislah (2017), Frontiers in Psychology: antecedents and outcomes of detachment from workMeeusen et al. (2013), Medicine and Science in Sports and Exercise: ECSS and ACSM joint consensus on overtraining syndromeAlbulescu et al. (2022), PLOS ONE: efficacy of micro-breaks for well-being and performanceHolt-Lunstad et al. (2010), PLOS Medicine: social relationships and mortality risk --- This episode is me reading the written newsletter, adjusted for the spoken word. Figures are rounded and citations are left out; everything is fully referenced in the written edition. AI assisted with research, drafting and adapting this piece for different formats. I chose the argument and examples, reviewed the evidence, edited the final text and take responsibility for every published claim. Nothing here is medical advice, and it is not a substitute for a conversation with your own doctor. If you are exhausted, sleeping badly, in pain, or worried about burnout, take it to your clinician rather than to a newsletter. If you are fighting to stay awake at the wheel, stop driving.
