How the Sleep Consistency Score is calculated

Your body has a built-in timing system (your circadian rhythm) that likes predictable cues. In plain language: if your sleep schedule swings wildly, your brain is constantly “relearning” when it should feel sleepy and when it should feel alert. That is why two people with the same total sleep time can feel very different—one feels steady, the other feels like they’re always catching up.

This calculator converts your weekly bedtime and wake time entries into minutes, then measures how much those minutes vary across the week. The core idea is simple: less variation = higher consistency. The calculator also looks at your sleep midpoint (halfway between bedtime and wake time), because midpoint drift is a quick way to detect a “schedule slide” where the whole sleep window moves later or earlier.

Each bedtime and wake time starts as a clock time like 11:30 PM or 6:45 AM. To do math on times, we convert them to minutes from midnight. For example:

• 11:30 PM → 23×60 + 30 = 1410 minutes
• 6:45 AM → 6×60 + 45 = 405 minutes

The tricky part is bedtime after midnight (like 12:30 AM). That looks “early” if you only count minutes from midnight. But in real life, 12:30 AM is usually later than 11:30 PM. To keep bedtimes clustered in a realistic late-night window, the calculator treats bedtimes in the morning (before noon) as “after midnight” and shifts them forward by 24 hours for internal calculations. That way, 12:30 AM becomes 24×60 + 30 = 1470 minutes.

For each day, we compute: duration = adjusted wake minutes − adjusted bedtime minutes. Then the midpoint is: midpoint = adjusted bedtime minutes + duration/2. Midpoint is useful because it captures the “center” of your sleep window. If you go to bed much later on weekends and wake much later too, your midpoint shifts later. That pattern often feels like jet lag on Monday.

Variability is calculated using a standard measure called standard deviation (SD). SD is basically the “typical distance” from the average. If your bedtime is almost the same every day, your bedtime SD will be small. If it jumps around, bedtime SD grows.

• Bedtime SD (minutes): how much your bedtime varies
• Wake SD (minutes): how much your wake time varies
• Midpoint SD (minutes): how much your sleep window drifts

Finally, we convert those SD values into a 0–100 score. We start at 100 and subtract penalties based on how many 15-minute “chunks” of variability you have. Bedtime and wake time are weighted similarly, and midpoint is weighted a bit less because it overlaps with the first two (it’s a helpful signal, but not independent).

The result is a score that behaves the way people expect: if your bed and wake times are within about 15–30 minutes most nights, you’ll typically land in the 80–95 range. If weekends drift by 2–3 hours, the score usually drops into the 40–70 range depending on how extreme the swing is.

Note: This is a practical, consumer-friendly scoring model designed for habit tracking and virality. It’s not a clinical sleep diagnosis tool, and you should not use it to self-diagnose sleep disorders.

How to read your score (and what to do next)

Your Sleep Consistency Score is a shortcut for one big question: How predictable is your sleep timing? When you improve predictability, many people notice better morning energy, fewer “random” sleepy afternoons, and a more stable mood. The best part is that consistency is often more controllable than perfect sleep duration.

• 85–100 (Elite consistency): Your timing is stable. Keep it up—this is “circadian-friendly” scheduling.
• 70–84 (Pretty consistent): Solid regularity with a few drift days. Small tweaks can push you into the elite zone.
• 50–69 (Inconsistent): Your schedule swings enough to create “mini jet lag.” Focus on stabilizing wake time first.
• 0–49 (Chaotic): Big swings. Pick one anchor (wake time) and move in 15-minute steps for 1–2 weeks.

If you want the biggest score jump with the least friction, do this: Keep wake time within a 30–45 minute window every day (including weekends) for one week. Many people find that bedtime becomes more predictable automatically, because the body starts getting sleepy at a more consistent time.

Weekend drift is common: you sleep later on Saturday and Sunday, then Monday feels rough. If you want to still “sleep in” a bit, try a compromise: keep wake time within 60 minutes of your weekday wake time, and take a short nap instead. That preserves consistency while still giving you recovery time.

Late bedtime is not automatically bad—some people are naturally later chronotypes. The real issue is big swings. If you’re a night owl, you can still have a high score by going to bed late consistently and waking at a predictable time.

Realistic weekly patterns (and what scores they tend to produce)

These examples help you sanity-check your result. Your exact score will depend on the full pattern, but the direction is consistent: tighter timing → higher score; bigger swings → lower score.

Mon–Fri: bed 11:00 PM, wake 7:00 AM. Sat: bed 1:30 AM, wake 10:00 AM. Sun: bed 12:30 AM, wake 9:00 AM. This is the classic “social jetlag” pattern. You might still get enough hours, but timing shifts. Scores often land around 55–75 depending on how big the drift is.

Every day: bed 1:00 AM ± 20 min, wake 9:00 AM ± 20 min. This person is late, but stable. That’s great for consistency. Scores often land around 80–95.

Mon–Wed: bed 10:30 PM, wake 6:00 AM. Thu–Sun: bed 2:00 AM, wake 10:00 AM. Even if each block is consistent, the week overall has two different schedules. Scores can land around 40–70. If shift work is unavoidable, aim for consistency within each shift block and use light exposure routines to smooth transitions.

Every day: bed 12:00 AM, wake 6:00 AM. Timing is consistent, duration is short. This may still score high (timing is stable), but it doesn’t mean you’re getting enough sleep. Consistency is one piece of the puzzle—not the whole puzzle.

If you want to evaluate both timing and quality, pair this tool with the Sleep Quality Score calculator.

Frequently Asked Questions

• What is a “Sleep Consistency Score”?

  It’s a 0–100 number that summarizes how steady your bedtimes and wake times are across a week. Higher scores mean your sleep timing is more regular.

• Do I need exactly 7 days?

  This calculator is designed around a week because most people have weekday vs weekend differences. For best results, fill all 7 days.

• If I’m a night owl, will I automatically get a low score?

  No. Being late is fine if it’s consistent. The score penalizes variability, not a specific bedtime.

• What if I went to bed after midnight?

  Enter the clock time (like 12:45 AM). The calculator adjusts internally so it’s treated as “later” than 11:30 PM, not earlier.

• Does this measure sleep quality?

  Not directly. It measures regularity of timing. Quality depends on many factors (environment, stress, sleep disorders, etc.). Pair this with a sleep quality tool for a broader picture.

• Can I use this for a challenge with friends?

  Yes—this is one of the best uses. Compare scores weekly, set a shared target (like 80+), and keep wake time drift small.