Why You Must Calculate Sleep Need Before Sleep Training
This is the piece of advice I find myself repeating most often: please don't start sleep training until you've worked out your baby's 24-hour sleep need. Skipping this step is one of the most common reasons sleep training doesn't go to plan, and it has nothing to do with the method you choose.
Sleep Training Relies on Sleep Pressure
Sleep training, regardless of the specific approach, is designed to help a baby learn to fall asleep independently and link their sleep cycles together. But that skill can only be learned under the right conditions, and the most important condition is sleep pressure: the natural drive to sleep that builds the longer your baby is awake. I've written about the biology behind this in more detail in What Is Adenosine, and Why Does It Matter for Baby Sleep?
Without knowing your baby's actual 24-hour sleep need, it's very easy to offer them more or less sleep than they need across the day, which throws sleep pressure off at exactly the times you need it working in your favour. Too much daytime sleep, for instance, and there won't be enough sleep pressure built up by bedtime, leading to resistance, prolonged settling, or split nights.
When this happens, the problem looks like a sleep training issue. It isn't. It's a sleep pressure issue, caused by a schedule that doesn't match the baby's actual sleep need, and no amount of consistency with a particular method will fix it.
Why Sleep Training Gets a Bad Reputation
This is, I think, where a lot of sleep training's bad reputation actually comes from. Parents try a method, it doesn't work, or it seems to make things worse, and the method itself gets the blame. Online, this often gets repeated as "sleep training doesn't work" or "it just causes more problems."
In my experience, it's rarely the method that's at fault. It's that the groundwork was skipped: the routine underneath the sleep training was never built around the baby's actual 24-hour sleep need, so the method never had a fair chance to begin with. Once the sleep need is recalculated and the routine adjusted to match it, sleep training tends to go far more smoothly, often without needing to change the actual training method at all.
This matters because it means a lot of families give up on something that could genuinely have helped, simply because it was attempted on top of the wrong schedule.
The Groundwork, In Order
If you're preparing for sleep training, here's the order I'd recommend working through:
Understand what a 24-hour sleep need is and why it's individual to your baby, covered in The Real Foundation of a Sleep Guide: Your Baby's Individual 24-Hour Sleep Need.
Track your baby's actual sleep for at least five days, calculate their true total, and build a routine around the right night-to-day split, covered fully in How to Calculate Your Baby's Sleep Need and Build a Routine Around It.
Only then begin sleep training, with confidence that the schedule itself is supporting the process rather than working against it.
The Takeaway
Sleep training teaches the skill of falling asleep independently. It can't manufacture sleep pressure that isn't there, and it can't undo the effects of a schedule that's mismatched to your baby's actual sleep need. Doing this groundwork first isn't an extra step to slow you down, it's what actually sets your baby up to succeed once training begins.
If you'd like help working through this properly, rather than guessing, my process always starts with understanding your baby's individual sleep need before we go anywhere near a sleep plan. You're welcome to book a free 15-minute introductory call to talk it through.