Sleep & heart · topic 3 of 5
Sleep and training
What the Guide’s sleep line is, and what it refuses to claim
The Guide compares two periods of your own record. Since sleep and training now come from the same period summary, it can lay them side by side: average night asleep, minutes awake in the night, sleeping heart rate, bedtime drift and the regularity index, beside MVPA, training minutes and strength days for the same two periods. Sleep joins the list of movers too — judged against the adult7–9 hour band rather than a direction, so 6 to 7 hours is an improvement and 8 to 9½ is not, while less time awake in the night, a lower sleeping heart rate, less bedtime drift and a higher regularity index count the way you would expect.
What the SLEEP line says.One sentence on what moved alongside what — “training rose 40% and sleep fell 35 minutes, with sleeping heart rate up 3”. It describes co-movement in your data. It never says one caused the other, because two periods of one person cannot show that: a hard block can shorten sleep, short sleep can make a block feel harder, and a work deadline can do both. The literature below is why the pairing is worth reading at all — short sleep tracks injury and worse endurance, and extended sleep has moved performance in small trials — but the line reports, and you interpret.
Hirshkowitz et al — National Sleep Foundation's sleep time duration recommendations, Sleep Health 2015
An expert panel's consensus on how much sleep is appropriate by age: 7–9 hours for adults 18–64, 7–8 for 65 and over. This is the band the Guide judges sleep against — a move toward it counts as an improvement, a move away as a slip, and a change from 8 to 9½ hours is neither a win nor a target. The AASM and Sleep Research Society's own 2015 consensus (Watson et al.) says the same thing from the other side: 7 or more hours on a regular basis for adults.
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Milewski et al — Chronic lack of sleep is associated with increased sports injuries in adolescent athletes, J Pediatr Orthop 2014
112 student athletes followed for 21 months. Those who slept under 8 hours a night had about 1.7 times the odds of injury of those who slept 8 or more — a larger effect than any training variable measured. Adolescents, not adults, and an association, not a mechanism; but it is the clearest single figure on why the Guide reads sleep and training load side by side rather than training alone.
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Mah et al — The effects of sleep extension on the athletic performance of collegiate basketball players, Sleep 2011
Eleven Stanford players extended their sleep toward 10 hours for 5–7 weeks. Sprint times fell, free-throw and three-point accuracy rose, and reaction time improved. Small and uncontrolled, but it is the experimental direction: performance moved when sleep moved. Verve does not prescribe 10 hours — it notes when sleep and training move together in your own record and leaves the interpretation honest.
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Fullagar et al — Sleep and athletic performance: the effects of sleep loss on exercise performance, and physiological and cognitive responses to exercise, Sports Medicine 2015
A systematic review of sleep loss and exercise. Restricted sleep worsens time-to-exhaustion, reaction time and mood more reliably than it worsens single maximal efforts, and it raises perceived effort at a given load — which is why a poor week of sleep can show up as harder-feeling sessions before it shows up in the numbers. The review also finds the reverse: hard training can disturb sleep. Neither direction is assumed in the Guide's sentence; it reports the co-movement and stops.
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