Most days, your energy is decided before you notice it: by how long you slept, whether you moved, what you ate at lunch, what is weighing on you, and what you drank the night before. The calculator above turns those six inputs into a score from 0 to 100 so you can see which one is costing you the most. This guide explains the physiology behind each input, how the score is built, what it can and cannot tell you, where to start, and when tiredness is a reason for a medical visit.
What drives day-to-day energy
Sleep is the biggest input. Through the day, a byproduct of energy use called adenosine builds up in the brain and makes you feel sleepy. Sleep clears it. Seven to nine hours clears it fully for most adults, and less than that leaves part of the bill unpaid. Consistency matters too. Your body clock times the morning rise in cortisol and the evening rise in melatonin around when you usually wake, so a schedule that shifts by hours from one day to the next puts both out of step with your day.
Movement is the second. Muscle that works regularly builds more mitochondria, the parts of the cell that turn fuel into usable energy, and takes up blood sugar more readily. Regular activity also deepens sleep. Sitting still most of the week does the reverse, and the first sign is usually feeling flat rather than feeling unfit.
Stress is a fuel problem in disguise. The stress response raises cortisol and adrenaline, which release sugar and fat into the blood for a short emergency. Held for weeks, the same signals keep your resting heart rate up, fragment sleep, and leave less in reserve for an ordinary afternoon.
Meal steadiness decides the afternoon. A lunch built on refined carbohydrate raises blood sugar fast, insulin follows, and the dip an hour or two later is the crash. Protein, fiber and fat slow the whole curve. A long gap without food, or too little water, adds to the dip. The early afternoon is also a natural low point on the body clock, so these habits land on top of a dip that is already there.
Alcohol borrows from tomorrow. It is sedating at first, so sleep comes quickly, but as the body clears it the second half of the night turns light and broken, with less of the deep and REM sleep that restores you. The effect scales with the amount, which is why the score counts each drink above three a week.
Age moves the baseline slowly. Cells make a little less energy from the same fuel, muscle is lost without training, and sleep gets lighter and shorter. None of that is sudden. It means the habits that mattered at 30 matter more at 60, which is why age counts in the score but weighs less than any single habit at its worst.
How the score is calculated
The score is a weighted self-assessment. It starts at 100 and subtracts points for each answer, with the size of the deduction set by how strongly that factor tends to move day-to-day energy. Sleep carries the most weight, then afternoon crashes, movement, stress, alcohol, and age. The table shows what each input moves and by how much.
| Input | What you enter | Points subtracted |
|---|---|---|
| Sleep | Hours a night | 9 for each hour under 7, up to 36. 5 for each hour over 9. |
| Afternoon crashes | How often | 8 for sometimes, 15 for often, 22 for daily. |
| Movement | Active days a week | 7 for each day under 3, up to 21. |
| Stress | Your own rating | 10 for moderate, 20 for high. |
| Alcohol | Drinks a week | 2 for each drink over 3, up to 18. |
| Age | Years | 0.3 for each year over 30, up to 15. |
The deductions add up and the total comes off 100. The result cannot go below 0 or above 100. The result card lists the three factors costing you the most, biggest first, and labels each one high (15 points or more), moderate (7 to 14) or low (under 7). The band is read off the final number.
| Band | Score | What it means |
|---|---|---|
| Thriving | 80 to 100 | Your habits are set up to support steady, reliable energy. |
| Steady | 60 to 79 | A solid baseline with a few habits worth tightening up. |
| Running low | 40 to 59 | Several everyday factors are pulling your energy down. |
| Depleted | 0 to 39 | Multiple drivers are stacking up, and small changes can add up fast. |
What the score is and is not
The score is directional. It tells you which of six habits is costing you the most, and roughly how much, so you know where to start. A sleep deduction of 27 points is a louder signal than an alcohol deduction of 4.
It is not a measurement. Nothing is tested. The inputs are your own estimates of a typical week, and the weights are a reasonable reading of how these factors tend to behave across large groups, not a formula fitted to you. Two people with the same score can have it for different reasons.
It is not a diagnosis. The calculator knows nothing about your iron, your thyroid, your breathing at night, your mood, or the medications you take. A high score does not rule out a medical cause of fatigue, and a low score does not establish one. Use it to find the biggest drain, change that one thing for a few weeks, and come back.
Where to start
Start with the factor at the top of your result card. If several are close, take them in this order.
- Protect sleep first. Seven to nine hours on a consistent schedule is the single largest lever in the score, and in most people’s weeks.
- Move daily, even briefly. Twenty to thirty minutes counts as an active day, and a short walk after lunch also blunts the afternoon dip.
- Build meals around protein. Protein, fiber and fat slow the rise and fall in blood sugar that a refined-carbohydrate lunch sets off, so energy holds steadier through the afternoon.
- Make room to recover from stress. A walk, slow breathing, or an evening off screens gives the stress response a chance to switch off.
- Keep alcohol modest. It fragments sleep more than most people realize, and the cost lands the next day.
When fatigue needs a clinician
A low score explains ordinary tiredness. It does not explain fatigue that is persistent, that arrived suddenly, or that comes with other symptoms. See a clinician if you notice unexplained weight change, low mood, breathlessness, heavy snoring, or waking unrefreshed after a full night, or if your habits are in good shape and the fatigue has not moved.
Thyroid conditions, anemia, sleep apnea and depression all present as low energy, and each has its own treatment once it is found. Low vitamin B12 or vitamin D and some medications can as well. None of these shows up in a lifestyle score. A clinician can order the tests that do.
NAD+ and cellular energy
Every input above comes down to the same chemistry. Inside each cell, food is broken down in steps, and the energy released is carried to where it is used. NAD+ (nicotinamide adenine dinucleotide) is a coenzyme that carries electrons through those steps, which puts it at the center of converting food into usable cellular energy. It is present in every cell, it also takes part in normal cell maintenance, and its levels decline with age.
Pallas offers a clinician-prescribed NAD+ program, a weekly subcutaneous injection with dosing matched to your health history, prescribed when a US-licensed clinician decides it is appropriate. Explore the NAD+ program.
Two things this calculator does not do. It does not measure NAD+ or any other biomarker, and nothing you take changes its score. The score reads your habits. A lab reads a biomarker. They answer different questions.
How to use this calculator
Answer for a typical week, not your best one. Enter your age in years. Set sleep to the hours you usually get on a work night, from 3 to 10. Set active days to the days a week you move for 20 to 30 minutes or more, from 0 to 7. Rate your stress low, moderate or high, and your afternoon crashes rarely, sometimes, often or daily. Enter your drinks a week as a number. The score, the band and the top three factors update as you change an answer. Nothing you enter is stored.
To see what a change would do, move one control and watch the number. An extra hour of sleep below seven is worth 9 points. A third active day is worth 7. Going from daily crashes to sometimes is worth 14.
Energy is the sum of a few ordinary inputs, and most of them are yours to change. Use the score to find the one that costs you the most, change it, and check again in a few weeks. If the number will not move, or the tiredness has a story the inputs cannot explain, a medical visit is the next step.