Slotwise reads four signals: sleep, sleepiness (KSS), reaction time (PVT) and heart-rate variability (HRV). It changes a student's calendar only when their own data says so, and every change comes with a reason in plain language.
GreenInside your personal normal. Nothing changes.
YellowLive during the day. Suggestions only, you decide.
RedMorning check only. Day rearranged, you can undo.
Three demo scenarios · every phone is the live app
X2b · RedReal baseline · simulated morning
Red morning check on exam day
Participant P04 · Mon 12 Oct, 08:00 · 9 nights of data
Level 1. Your body needs recovery today: you slept 3 h 30, your 3-night HRV average (60 ms) is below your normal (65–69 ms), and you feel sleepier and slower. Slotwise rearranged today before it starts.
Signal
Today
Your normal
Effect
Sleep
3 h 30
6 h 47–7 h 43
Big
HRV, 3 nights
60 ms
65–69 ms
Trigger
Reaction (PVT)
362 ms
323–337 ms
Medium
Sleepiness (KSS)
9
7.2–8.0
Medium
Sleep
+4.0
Reaction
+2.2
Sleepiness
+1.6
HRV
+1.6
Overload score · a normal day ≈ 09.3
Level 3. If P04 had slept their usual 7 h, today would be yellow: the gym stays and only a break is added after the exam.
Low overnight HRV, short sleep and worse sleepiness or reaction time? Slotwise turns the day red and rearranges it before it starts.
X2a · YellowReal data
Live yellow warning during study
Participant P05 · Wed 14 Oct, 19:40 · 10 days of data
Level 1. Your HRV just dropped to 36 ms, below your usual daily low, and you feel sleepier and react slower than on a normal evening. Take a 20-minute break now. Move the hard part to Thu 11:30?
Signal
Today
Your normal
Role
Lowest HRV
36 ms
37–59 ms
Trigger
KSS, evening
8
5.5–7.2
Confirms
PVT, evening
372 ms
323–353 ms
Confirms
Sleep
7 h 28
7 h 26–8 h 52
Normal
Reaction
+1.1
Sleepiness
+1.0
HRV
+0.5
Sleep
+0.5
Overload score · a normal day ≈ 03.2
Level 3. Why only yellow? Daytime HRV is affected by movement and posture, and P05 slept normally. Red needs low overnight HRV and short sleep, checked in the morning.
HRV drops during the day? Yellow warning: take a break, go lighter, see why.
X1 · Green + tipSimulated
Chosen chronotype vs real data
Simulated student · Thu 15 Oct, 09:00 · 12 days of data
Level 1. You chose evening type, but your afternoons are just as good as your evenings. Try moving Statistics (8/10) from 20:00 to 15:00 for the next 2 weeks.
Measure
15:00
20:00
Gap
Sleepiness (KSS)
4.2
4.4
0.2
Reaction (PVT)
318 ms
321 ms
3 ms
Usual day-to-day change
sleepiness 0.9 · reaction 14 ms
Bigger
Best slot = lowest sleepiness. A gap smaller than your own day-to-day change fits an intermediate type. How sure: 12 days of data.
Level 3. If 15:00 turns out clearly harder than 20:00 over the 2 weeks (more than your usual 0.9 swing), Slotwise moves it back.
Chosen chronotype vs your real data: Slotwise shows the mismatch and suggests trying a better study time for two weeks.
How Slotwise decides
Green
Every signal is inside the student's personal normal range. Nothing changes. HRV above normal never triggers a change either.
Yellow, live during the day
HRV drops below the usual daily low and evening sleepiness or reaction time confirms it. A break and a lighter rest of the day are suggested. Moving tasks is only suggested, with Move and Keep.
Red, 08:00 morning check only
Low 3-night overnight HRV and short sleep and higher sleepiness or slower reactions. The day is rearranged before it starts, with Keep and Undo.
Level 1
Notification
One or two sentences: what is happening and what Slotwise did or suggests. Buttons: Keep, Undo, Why, or Move and Keep.
Level 2
Why?
The top reasons in the student's own units against their own usual, each labelled small, medium or big. The bars are the signal's contribution to the overload score.
Level 3
What if…
A counterfactual the student can play with, like a sleep slider that shows when the day flips from red to yellow.
Personal normal rangeown average ± 0.5 SD
From HRV-guided training research (Vesterinen 2016, Javaloyes 2019). HRV is judged on a 3-night rolling average.
Trust in your own dataweight = n / (n + 3)
n = days of check-ins. Day 9 gives 75% personal data and 25% the general model from the sign-up profile.
Overload scoreΣ distance from own average, in own SDs
Direction-corrected so that higher always means more strain. A normal day scores about 0. HRV never acts alone.
Put Slotwise on your phone
Install it like an app
iPhone: open this site in Safari, tap Share, then Add to Home Screen.
Android: open it in Chrome, tap the ⋮ menu, then Install app.
It opens full screen from your home screen, works offline, and keeps your data on your phone.
Scan with your phone
Use the real app
Onboarding, swipeable check-ins with the sleep dial and the sleepiness (KSS) slider, the 3-minute reaction test (PVT), a calendar where you add activities and get explained suggestions. On this site your data stays on your own device.
