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Individual Differences, Aging & Recovery Adaptation

Human Performance & Health › Sleep & Recovery › Individual Differences, Aging & Recovery Adaptation

This page covers two measured kinds of difference: how sleep changes across the lifespan, and how much people differ in their response to the same training.

Aging and Sleep

Sleep changes with age, even in healthy people. A meta-analysis of 65 studies and 3,577 healthy subjects aged 5 to 102 found that in adults total sleep time fell by roughly 10 minutes per decade, slow-wave sleep by about 2 percentage points per decade, and time awake after sleep onset rose by roughly 10 minutes per decade from about age 30; after 60, “only sleep efficiency continued to significantly decrease” (Ohayon et al., 2004). In 149 healthy men aged 16 to 83, deep sleep fell sharply from early adulthood to midlife and growth hormone secretion dropped in parallel, while later in life slow-wave sleep changed little and time awake rose (Van Cauter et al., 2000).

Differences in Training Response

In a standardized 20-week training study, the heritability of gains in maximal oxygen uptake (VO2max) was “estimated at 47%,” and participants carrying 9 or fewer of 21 favorable gene variants improved by 221 ml/min on average, against 604 ml/min for those carrying 19 or more (Bouchard et al., 2011). The detail is on Fitness.

Tracking Personal Signals

The orthosomnia case series on the optimization page is the documented risk of tracking sleep for its own sake (Baron et al., 2017).

What Comes Next

→ The last page in the series is Physical Recovery Modalities.

GoldBlock Workshop is educational. We explain how the body works and what the research says. We do not diagnose, treat, or give personal medical advice. Talk to a qualified professional about persistent sleep or recovery problems, especially if symptoms are severe or ongoing.

Sources and further reading

  • Ohayon et al., “Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals,” Sleep (2004; read 2026-10-18). PubMed
  • Van Cauter et al., “Age-related changes in slow-wave sleep and REM sleep and relationship with growth hormone and cortisol,” JAMA (2000). PubMed
  • Bouchard et al., “Genomic predictors of the maximal O2 uptake response to standardized exercise training programs,” Journal of Applied Physiology 110(5):1160-1170 (2011). Abstract read 2026-10-19 (Duke Scholars). Duke Scholars