How much sleep do you actually need?
The short answer: 7 to 9 hours for most adults, and toward the top of that range if you train hard. About 1 in 40 people genuinely thrives on less; the rest of us just adapt to feeling slightly degraded and call it normal.
What the ranges actually mean
Large studies converge on 7 to 9 hours for adults, with health risks rising on both ends. The catch is individual: your number is set largely by genetics, and the honest test is how you function without an alarm after two weeks of consistent bedtimes.
Signs you are under-slept are unglamorous: needing an alarm to wake, afternoon crashes, sugar cravings, and a resting heart rate that sits higher than your usual baseline.
Why training raises your requirement
Muscle repair, glycogen restocking and the hormones that drive adaptation, growth hormone in particular, do their heaviest work during deep sleep. Cut the night short and you literally cut the recovery.
Studies on athletes show reduced sleep drops next-day power output and increases injury risk, while extending sleep improves sprint times and accuracy. Sleep is not separate from training; it is the second half of it.
Finding and protecting your number
Pick a fixed wake time, move bedtime earlier in 15-minute steps, and watch how you feel at the same hour each afternoon. Two weeks of data beats any generic rule.
Equil reads your sleep automatically from Apple Watch and Apple Health, builds a bedtime and wake schedule around your life, and adjusts your training and calorie targets on the days your body clearly did not recover.
Stop tracking by hand
Equil reads your food, glucose, sleep and training, then adjusts your plan in real time. Not another logger, a coach.
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