This is kind of interesting too. Especially this passage:
Due to availability, 2 different models of activity monitor—produced by a sole manufacturer—were used in this study (Actiwatch-64 and Actical Z-series; Philips Respironics, Bend, OR). The monitors were configured to sum and store data in 1-minute epochs based on activity counts from a piezoelectric accelerometer with a sensitivity of 0.05 g and a sampling rate of 32 Hz. Data from the sleep diary and activity monitor were used to determine when participants were awake and when they were asleep. Essentially, all time was scored as wake unless: (1) the sleep diary indicated that the athlete was lying down attempting to sleep and (2) the activity counts from the monitor were sufficiently low to indicate that the athlete was immobile.[20] When these 2 conditions were satisfied simultaneously, time was scored as sleep.
This seems to indicate that “sleep” for this study was pillow time. Not necessarily actually being “asleep” I’m also noting that while the study seems to indicate that 8.3 hours is how much sleep athletes need, these are all people in their early to mid-twenties. Do masters athletes have different needs?
I’m trying to skim stuff as I’m working so I could be missing some things, but it appears that sleep is kind of a fuzzy concept still.