😴 Diagnose the Sleep Problem
Four quick questions. Top 3 most likely causes for tonight, with fixes. Built for use at 2 AM.
How this tool actually helps
Five quick steps. Most parents can complete this in under 2 minutes even at 2 AM.
- 1Pick your baby's age
Different ages have different normal sleep patterns and likely causes. We adjust the diagnosis based on developmental stage.
- 2Choose the main problem
Won't fall asleep, frequent waking, waking too early, short naps, or crying in sleep. Pick the one that fits best. You can also pick More Than One if multiple apply.
- 3Tick the symptoms you see
Multi-select. Pulling ears, drooling, red face, kicking legs, etc. The more symptoms you tick, the more accurate the diagnosis.
- 4Add recent context
Anything that's changed lately. New tooth coming, missed nap, started daycare, moved house. These often hold the key.
- 5Click Diagnose
You get the top 3 most likely causes ranked by probability, with immediate fixes for tonight and prevention tips for tomorrow. We'll also flag any red flags that mean you should see a doctor.
I built the first version of this tool in my head at 3 AM when my 7-month-old was on his fifth wake-up. I had read four different blog posts, two Reddit threads, and a WhatsApp forward. They all said different things. I just wanted someone to tell me what was MOST likely so I could try ONE thing. This tool is that. It is not magic. But it gets you to the most likely cause in under 2 minutes, with one thing to actually try. That is usually all a tired parent needs.
This tool is a triage guide for normal baby sleep issues based on common pediatric sleep knowledge. It is NOT a substitute for your GP. If your baby has a fever, breathing issues, lethargy, persistent vomiting, or you as a parent are not coping — the doctor wins, every time. The red flag banner in your result will tell you if a doctor visit is needed.
What's actually going on when your baby won't sleep
The biology behind those 2 AM meltdowns. Useful to understand even when you're too tired to read.
Wake windows by age — the single most useful number
If you remember one thing from this whole page, remember wake windows. The time baby is awake between sleeps. Too short, not tired enough. Too long, overtired (and ironically harder to settle).
| 0-3 months | 45-90 minutes |
| 4-5 months | 75-120 minutes |
| 6-8 months | 2-2.5 hours |
| 9-12 months | 2.5-3.5 hours |
| 13-18 months | 3.5-4.5 hours |
| 18-24 months | 4-6 hours |
| 2-3 years | 5-6 hours (1 nap day) |
The 4-month sleep regression — not a regression, a permanent change
The most misunderstood phase. Around 4 months, baby's sleep architecture changes permanently. Before 4 months, baby sleep is mostly deep with brief stirrings. After 4 months, baby sleep matures into adult-like cycles — light, deep, REM, repeat — with full awakenings every 45-90 minutes between cycles.
The change is biological and irreversible. Babies who used to drift back through cycle ends now WAKE UP fully at the end of each cycle. They need to learn to bridge these cycles — either by self-soothing back to sleep, or by getting help from a parent.
Sleep associations — how good intentions create night wakings
An association is whatever the baby is doing when they FALL ASLEEP. If you rock the baby until they're asleep then transfer to cot, the baby's brain learns "I sleep when being rocked." Then when they wake briefly between cycles (which happens every 45-90 min after 4 months), they look around and find themselves in a different situation than when they fell asleep. The brain says "WAIT, this is wrong" and the baby wakes fully, crying.
The fix is putting baby down DROWSY but AWAKE. They learn the cot itself is where sleep happens. Then between cycles, they wake briefly, see the same situation, and drift back to sleep without needing you.
Bedtime routine — signals matter more than time
A 20-30 minute bedtime routine, done the same way every night, signals to baby's brain that sleep is coming. The body starts producing melatonin in response. The routine ITSELF is the trigger, not the clock time.
The British summer problem — room temperature is huge
Optimal baby sleep room temperature is 22-24°C. Most British summer bedrooms without AC sit at 30-34°C through the night. That alone causes 60-70% of "mysterious" night wakings in British babies through April-October.
White noise — what it does and why it helps
The womb is LOUD. Roughly 70-80 decibels. Louder than most living rooms. Newborns are physiologically wired for noise during sleep. Silent rooms feel wrong to them. White noise (steady, low-frequency sound) mimics the womb environment and masks household sounds like doors opening.
Use a white noise machine, a fan on low, or a phone app (search "white noise sleep"). Continuous, not intermittent. Volume around the level of a shower running (50-65 dB), played throughout sleep.
Day sleep affects night sleep — how much, when, where
Counterintuitive truth: a well-napped baby sleeps BETTER at night, not worse. Skipping naps to "tire them out" backfires almost every time. The body produces cortisol when sleep-deprived, which keeps them wired and awake.
When sleep issues mean a doctor visit
Most sleep problems are normal, age-appropriate, and resolve with time. But sometimes they signal something medical. Red flags below need a GP check, not a calculator.
British sleep myths, gently set straight
Things tired parents actually ask
My baby cries the moment I put her in the cot. What is the fastest thing to try?
How do I know if it is hunger or a sleep association?
Is letting my baby cry harmful?
My in-laws says my baby is hungry every time she cries. Is she right?
What is the 4-month sleep regression and is it permanent?
Should I sleep train my baby? At what age?
What are wake windows and how do I use them?
Is co-sleeping safe?
How much sleep does my baby actually need?
When should I see a GP about sleep issues?
How baby sleep care actually works in the UK
UK pediatric care runs through the NHS. Generally well organised. Can feel slow at peak times. Your first call is usually NHS 111. Free, 24/7. They triage what is going on and tell you what level of care to seek. Sometimes a GP appointment via e-Consult. Sometimes A and E. Occasionally an ambulance. Out of hours GP services run evenings and weekends. Walk in centres and Urgent Treatment Centres handle the mid range stuff. A and E is for genuine emergencies, not routine fever queries, where you can wait many hours. For babies under 3 months though, A and E is the right call regardless. The NHS Pharmacy First service can also handle minor childhood things now without a GP appointment.
In the UK, call NHS 111 for non-emergency advice 24/7. For emergencies, call 999. Your Health Visitor is a valuable resource during weekday hours. Pharmacies like Boots offer free advice through the Pharmacy First service. Many GP practices have an after hours triage line.
What British mums actually deal with
British mums often feel pressure to wait it out before bothering the NHS. This is wrong thinking. NHS 111 was designed for exactly these calls. Staff are trained to triage and there is genuinely no judgment for calling. Health Visitors are an underused resource. They expect to hear about concerns in young babies. They can advise on what is normal during teething (mild temperature elevation, yes). True fever above 38 Celsius is something else and worth a proper assessment. British medical practice runs more conservative on medication than American practice. Calpol is the workhorse. Talk to your GP or pharmacist before alternating with Nurofen, NICE specifically does not recommend routine alternating.