Wellness Calculators
Free wellness calculators for sleep debt, sleep timing, daytime sleepiness, and daily health habits. Science-based tools for better rest and daily routines.
Wellness Calculators - Build Better Daily Habits
Good health is built on daily habits: consistent sleep, adequate hydration, and mindful routines. The calculators below help you turn generic advice into precise, personalised targets grounded in research.
These are reference and self-screening tools, not a diagnosis. The Epworth Sleepiness Scale, Pediatric Epworth Sleepiness Scale, and AHI calculators reproduce standardized clinical screening questionnaires used as a first step toward evaluating sleep apnea and narcolepsy - a high score or AHI value means “talk to a doctor about a sleep study,” not “you have sleep apnea.” Only a clinician interpreting an actual polysomnography (sleep study) can diagnose a sleep disorder.
Sleep Timing
Clinical Sleep Screening
The Sleep Calculator and Sleep Debt Calculator are pure scheduling and tracking tools with no clinical dimension - they help time bedtimes to 90-minute sleep cycles and quantify how much sleep debt has accumulated over a week. The three screening tools are different: the Epworth Sleepiness Scale and its pediatric counterpart reproduce the standardized questionnaire clinicians use as an initial daytime-sleepiness screen, while the AHI Calculator reproduces the severity math applied to actual sleep study data - both are the same tools a sleep clinic uses, but interpreting the result and deciding on treatment still requires a clinician.
Who Uses These Calculators
Anyone trying to improve sleep quality uses the sleep timing calculators to plan bedtimes and track accumulated sleep debt after a poor week. People wondering whether their daytime sleepiness is worth investigating use the Epworth Sleepiness Scale as a first, informal checkpoint before deciding whether to raise it with a doctor. Patients who have already had a sleep study, and clinicians or students reviewing sleep medicine coursework, use the AHI calculator to check severity classification math against a known result - it is not intended to replace the sleep study itself.
Frequently Asked Questions
How many hours of sleep do adults need?
The National Sleep Foundation recommends 7 to 9 hours per night for adults aged 18 to 64, and 7 to 8 hours for adults 65 and older. Teenagers (14 to 17) need 8 to 10 hours; school-age children need 9 to 11 hours. Individual variation exists, but consistently sleeping fewer than 7 hours is associated with increased risk of cardiovascular disease, obesity, and impaired cognitive function.
What is a sleep cycle and how long does it last?
A sleep cycle is one complete progression through all sleep stages: NREM Stage 1 (light sleep), NREM Stage 2 (light sleep), NREM Stage 3 (deep slow-wave sleep), and REM (rapid eye movement sleep). One full cycle takes approximately 90 minutes. Adults complete 4 to 6 cycles per night, with deeper sleep concentrated in earlier cycles and REM increasing toward morning.
Why does waking at the end of a sleep cycle feel better?
Waking mid-cycle, especially during deep NREM Stage 3 sleep, causes sleep inertia: grogginess, disorientation, and reduced cognitive performance that can last 15 to 60 minutes. Timing your alarm to coincide with the end of a 90-minute cycle means you wake during lighter NREM Stage 1 or 2, where the body is already transitioning toward wakefulness. The Sleep Calculator automates this timing for you.
Does a high Epworth or AHI score mean I have sleep apnea?
No. A high Epworth Sleepiness Scale score (above 10) or an elevated AHI value are both screening indicators, not a diagnosis. Excessive daytime sleepiness has many possible causes beyond sleep apnea, including insufficient sleep, depression, medication side effects, and other sleep disorders, and only an in-lab or validated home polysomnography interpreted by a sleep physician can actually diagnose obstructive sleep apnea. If your score is elevated, the appropriate next step is to discuss it with a doctor and ask about a sleep study - not to self-treat based on the calculator result.