Baby Nap Navigator

Overview

Every new parent eventually asks the same 3AM question: "the baby woke up at 2:05 — when is the next nap?" The answer lives in wake windows: the age-dependent stretch of awake time after which an infant's sleep pressure tips from "easy to settle" into "second wind cortisol spiral". Nailing the window is the difference between a 12-minute rock-to-sleep and a 45-minute scream-lullaby marathon.

This skill turns a log of wake-up times into:

1. Age-banded wake windows (evidence-informed ranges from the empirical tables pediatric sleep consultants use — 0–6 weeks through 2+ years).
2. A projected next-24h schedule — next nap start, expected length, the one after that, and a bedtime window.
3. Drift detection — is the morning nap creeping later day by day? (That's the classic 2→1 transition signal.)
4. Overtiredness flags — late-day wake windows stretched past the band produce a cortisol-second-wind warning and a "pull bedtime earlier" correction.
5. A 7-day report — naps per day, average lengths, night onset, and which days broke.

It is deliberately a timing instrument, not a sleep-training method. It never tells you to let a baby cry, never overrides a pediatrician, and bakes the safe-sleep rules (AAP: back-to-sleep, bare crib, no weighted blankets) into every printed plan.

When to Use

• "Baby woke at 6:40, when should her first nap be?"
• "Construct today's nap schedule" / "project the next 24 hours"
• "Is he ready to drop from 3 naps to 2?" (drift analysis)
• "She's been fighting bedtime — are the naps too late?"
• Caregiver handoff: print a day plan for a grandparent/nanny
• Tracking a week of naps and getting a summary report

Don't use for: medical sleep problems (apnea, reflux pain, failure-to-thrive sleep disruption → pediatrician), sleep-training method selection (Ferber/Chair/whatever — out of scope by design), or night-waking feed plans for young infants (hunger-driven, not clock-driven).

How It Works — Numbered Workflow

1. Profile once: record age in weeks (log does this automatically) and timezone-free clock times (works with any local HH:MM).
2. Log each wake-up (and optionally each nap start/end). The state file is a plain JSON you own — no cloud, no account.
3. Ask now: given the last wake time, print the current window (earliest–latest nap start) and the ideal start (window midpoint).
4. Run projections: simulate the rest of the day — each wake → window midpoint → age-typical nap length → next window — through a bedtime window, flagging any wake window that exceeds the band (⚠️ OVERTIRED RISK).
5. Run drift weekly: linear regression of nap-start times over the last 7–14 days per nap slot; >10 min/week creep in the morning nap + shortening second nap = transition brewing.
6. Run report for the weekly picture and hand it to whoever covers the next shift.

Wake-Window Table (built into the script)

Read the full rationale, transition signals, and the "watch the baby, not the clock" caveats in references/wake-window-science.md.

Quick Start

# one-time: age in weeks at first log
python3 scripts/nap_navigator.py log --age-weeks 22 --wake 06:50
python3 scripts/nap_navigator.py log --wake 09:35            # woke from nap 1
python3 scripts/nap_navigator.py log --wake 12:40

# what's happening right now
python3 scripts/nap_navigator.py now          # last wake + age → current window

# full day projection from the last wake
python3 scripts/nap_navigator.py projections  # next 24h schedule + OT flags

# weekly analytics
python3 scripts/nap_navigator.py drift        # nap-creep regression
python3 scripts/nap_navigator.py report       # 7-day summary

State lives in nap_state.json next to the script (override with --state /path/x.json). Times are your local clock; the script never fetches anything — pure offline stdlib.

Interpreting the Output

• Window 14:12–15:12 means: earlier edge = drowsy-cue zone (best settle odds), later edge = cortisol risk zone. The midpoint is the default suggestion.
• ⚠ OVERTIRED RISK on a projected window means the schedule ran long — the fix is almost always shorten the previous nap or pull bedtime 15–20 min earlier, not "tire the baby out more".
• Drift verdicts: STABLE, CREPING (n min/wk) — watch for 2→1 transition, REGRESSION (later bedtime pressure).
• Every printed plan ends with the safe-sleep footer: baby on back, firm flat surface, nothing in the crib, room ~20–22°C, no hats/weighted items.

Common Pitfalls

1. Chasing the clock instead of the baby. Windows are bands, not train times. Yawning, pink eyebrows, gaze-averting, fist-to-ear — cues beat the midpoint every time. The script says this too, because at 3AM nobody remembers.
2. One bad nap day ≠ a schedule change. Regressions need 3–5 consecutive days before you conclude anything. drift uses 7+ data points for exactly this reason.
3. Bedtime too late "so he'll sleep in". The classic trap: late bedtime → OT cortisol → night wakes → worse mornings. The projection pulls bedtime earlier on bad-nap days.
4. Dropping a nap too early. Most 3→2 drops happen 7–9 months, 2→1 at 13–18 months. Dropping at the first sign of a nap strike buys you a month of 35-minute naps. Check drift first.
5. Fourth-trimester expectations. Under ~12 weeks, circadian rhythm barely exists. The script marks this band "PATTERN-SEEKING, NOT SCHEDULING" and refuses to shame anyone.
6. Using it as a medical device. Snoring, pauses in breathing, feeding-pain wakes, or a baby who never sleeps more than 20 min for days → pediatrician, not a projection.

Verification Checklist

• log --age-weeks N --wake HH:MM wrote nap_state.json (cat it)
• now prints a window consistent with the age band table
• projections lists ≥2 future events and flags any window over the band max
• drift prints a verdict (needs ≥3 logged days for slope; says so otherwise)
• report covers each logged day with nap counts and lengths
• No network calls anywhere in the script (grep for requests|urllib|socket — must be empty)

One-Shot Recipes

"She woke at 6:50, it's 8:55 and she's rubbing eyes — nap now or push?"

python3 scripts/nap_navigator.py log --age-weeks 22 --wake 06:50
python3 scripts/nap_navigator.py now
# window 08:50–09:40 → 8:55 is inside the drowsy zone: go now.

Handoff sheet for the grandmother:

python3 scripts/nap_navigator.py log --age-weeks 30 --wake 07:05
python3 scripts/nap_navigator.py projections
# print the output; it includes cues-to-watch and the safe-sleep footer.

"Is the morning nap creeping late?"

python3 scripts/nap_navigator.py drift   # after ≥7 days of logs

License & Disclaimer

MIT. Informational scheduling aid for caregivers; not medical advice, not a sleep-training program. Safe sleep per AAP guidance: infant on back, firm flat sleep surface, no loose bedding, no weighted items, room-sharing for at least the first 6 months. When in doubt about any sleep problem — call your pediatrician.