By Jordan Sellar
AFLW High-Performance Manager
Sleep matters. It is the most valuable recovery modality available to us — essential for producing peak performance, maintaining health, and feeling your best.
We hear this constantly from coaches, healthcare professionals, online articles, and the devices on our wrists.
As a performance coach, I believe it's critical that the athletes I work with understand why. What actually happens during sleep that makes it so important — and what can we do to improve it and find a genuine edge through recovery.
It starts with understanding sleep a little better.
Sleep is dynamic — not all time spent sleeping is equal. We sleep in cycles, moving through four distinct phases:
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Light Sleep
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Deep Sleep (Slow Wave Sleep)
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Rapid Eye Movement Sleep (REM)
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Wake
Each cycle takes roughly 90 minutes, meaning a full night's sleep should yield 4–6 complete cycles.
Light Sleep serves as the transition from wakefulness into deeper stages.
Deep Sleep is best understood as the Physical Recovery Phase. This is when the majority of the body's daily Growth Hormone production and secretion occurs — a process essential for tissue growth and repair. Growth Hormone release triggers downstream anabolic activity driving protein synthesis, collagen synthesis, and bone remodelling. For athletes and active individuals, this is significant — it is the mechanism through which we convert training stimulus to physiological improvement.
REM Sleep is the Mental and Cognitive Recovery Phase. During REM, information is transferred from the hippocampus to the cerebral cortex for long-term storage. The brain effectively "replays" the day's waking activity — repeatedly reinforcing neural signals to the cortex until memories are encoded strongly enough that short-term hippocampal recall is no longer required. This process underpins motor learning and procedural memory, meaning skill acquisition, pattern recognition, and decision-making all benefit. These capacities are critical for execution and composure in high-leverage competition, but they also enhance the quality and retention of everyday practice and learning.
Sleep quality can be objectively measured through Photoplethysmography (PPG) — a light-based sensor technology that tracks heart rate, which presents a distinct signature across each sleep phase. By analysing these heart rate patterns, we can quantify how much time is spent in Light, Deep, and REM sleep each night. An efficient night's sleep approximates: 50% Light Sleep, 22% REM, 22% Deep Sleep, and 6% Awake.
Maximising sleep quality and efficiency is a cornerstone of athletic recovery. Below are several recommendations I consistently provide to the athletes I work with.
Maintain a Consistent Routine
The body's circadian rhythm depends on regularity to function optimally. When sleep and wake times are consistent, the brain begins to anticipate these transitions — improving the timing and efficiency of key hormonal processes, including melatonin secretion in the evening and cortisol release in the morning.
Where possible, this means going to bed early. Aligning your circadian rhythm with the natural decline in light and temperature each evening reinforces the cues that make sleep onset faster and more efficient.
The 10-3-2-1 Rule
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10 hours before bed: no caffeine
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3 hours before bed: no large meals
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2 hours before bed: no work
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1 hour before bed: no screens
Caffeine is a stimulant that directly suppresses drowsiness and elevates alertness — its half-life means evening consumption can meaningfully disrupt sleep architecture. Food digestion demands metabolic activity and elevates core body temperature, both of which reduce Deep Sleep efficiency. Work and screen exposure elevate cortisol and suppress melatonin production, interfering with the circadian processes that make sleep restorative.
Hydrate Well, Early
Hydration supports sleep quality through improved thermoregulation, electrolyte balance, and reduced nocturnal awakenings.
Adequate hydration facilitates the gradual reduction in core body temperature that characterises quality sleep onset — enhancing circulation and heat dissipation through the skin. Electrolyte balance further supports nerve signalling, muscle relaxation, and cardiac rhythm regulation during sleep.
Critically, hydration should be distributed throughout the day. Large fluid intake in the 1–2 hours before bed increases the likelihood of overnight waking to urinate — a simple but meaningful disruption to sleep continuity.
