Age-Based Sleep Requirement Calculator
Calculate your personalized nightly sleep target based on age, physical activity, stress, and health status. Use it to set evidence-based sleep goals that match your actual lifestyle demands.
Last updated: September 2026
Formula below · 1 source (Wikipedia) · Updated Sep 2026
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About this calculator
Sleep needs are shaped by age, daily energy expenditure, psychological stress, and overall health. The base requirement is the midpoint of the AASM/National Sleep Foundation range for your age: infants (under 1) 14 hours, toddlers (1–2) 12.5, preschoolers (3–5) 11.5, school-age children (6–12) 10.5, teenagers (13–17) 9, adults (18–64) 8 and adults 65+ 7.5 hours. The formula is: sleepNeeded = max(lowerLimit, base × (1 + (activityLevel − 1.2) × 0.2) × stressLevel × healthStatus). The activity factor adds about 3.5% for light exercise, 7% for moderate and 10.5% for heavy exercise (about 50 extra minutes for an adult), reflecting the extra recovery demand of training. The stress factor is 0.9 (low), 1.0 (moderate) or 1.1 (high) and the health factor 0.95 (excellent), 1.0 (good) or 1.15 (health issues or recovery). The result is never below the lower end of the recommended range for your age (7 hours for adults), because sleeping less than that is not recommended for anyone. These lifestyle factors are modelling choices layered on the age guidelines, not part of them.
How to use
Example: a 25-year-old (base 8 hours) who does moderate exercise (1.55), has high stress (1.1) and good health (1.0). Step 1 – Activity factor: 1 + (1.55 − 1.2) × 0.2 = 1.07. Step 2 – Apply all factors: 8 × 1.07 × 1.1 × 1.0 = 9.42 hours. This person should aim for roughly 9–9.5 hours given the training load and stress. A sedentary, low-stress 25-year-old in excellent health gets 8 × 1 × 0.9 × 0.95 = 6.84, raised to the 7-hour adult minimum.
Frequently asked questions
How many hours of sleep do children and teenagers need compared to adults?
The National Sleep Foundation recommends 9 to 11 hours for school-age children (6–13), 8 to 10 hours for teenagers (14–17), and 7 to 9 hours for adults (18–64). Adolescents have a biological shift in circadian rhythm that delays their natural sleep onset to later in the evening, making early school start times particularly harmful for their sleep totals. Children need more sleep because growth hormone is predominantly released during slow-wave sleep, and neural development depends heavily on both REM and deep NREM stages. Chronic under-sleeping in children is associated with attention deficits, behavioral problems, and impaired learning.
Does high physical activity increase how much sleep you need?
Yes — vigorous physical exercise meaningfully increases sleep need because sleep is the primary window for muscle repair, glycogen replenishment, and growth hormone secretion. Athletes and people doing heavy manual labor often require 9 or more hours for full recovery, compared to the 7–8 hours sufficient for sedentary individuals. Deep NREM slow-wave sleep increases in proportion to prior physical activity, suggesting the body actively prioritizes physical restoration. If you are training intensively and waking feeling unrestored, insufficient sleep duration is often the first variable to address before adjusting nutrition or training load.
Why do stress and poor health increase your sleep requirement?
Psychological stress activates the HPA (hypothalamic-pituitary-adrenal) axis and elevates cortisol, which directly fragments sleep architecture and reduces restorative slow-wave sleep — meaning your body needs more total time in bed to achieve the same depth of recovery. Illness and chronic health conditions similarly increase the metabolic demand for immune activity, tissue repair, and inflammation resolution, all of which are most efficient during sleep. Studies show that sleep-deprived individuals mount a weaker immune response to vaccines and infections. The calculator's stress and health multipliers reflect this: a person under high stress with a health condition may need 30–60 minutes more sleep nightly than a healthy, low-stress peer of the same age.