The Happyly Sleep Library
Research-backed guides written for exhausted parents. Every article is based on peer-reviewed pediatric sleep research, cited by author and paper.
Published (9)
The 4-month sleep regression: what is really happening and what helps
A research-backed guide to the 4-month sleep regression. Why it happens, how long it lasts, what to do tonight, and when to call your pediatrician.
Based on: Scott Rivkees, Alexander Borbely, Marie-Helene Pennestri + more
9 min read · Updated April 2026
How to help your baby sleep through the night
A research-backed guide to helping your baby sleep through the night. Honest timelines, the biology behind sleep consolidation, and what parents can actually do.
Based on: Marie-Helene Pennestri, Jacqueline Henderson, Alexander Borbely + more
8 min read · Updated April 2026
Bedtime routines that actually work
A research-backed guide to bedtime routines for babies and toddlers. Why routines work, what to include, how long they should be, and what to do when they stop working.
Based on: Jodi Mindell, Avi Sadeh, Monique LeBourgeois + more
7 min read · Updated April 2026
Nap transitions: when to drop from 3 to 2 to 1 nap
A research-backed guide to nap transitions. When to drop from 3 to 2 to 1 nap, how to manage the messy middle, and what to do when bedtime falls apart.
Based on: Ivo Iglowstein, Barbara Galland, Marc Weissbluth + more
8 min read · Updated April 2026
Newborn sleep: realistic expectations for the first 3 months
A research-backed guide to newborn sleep. What is normal, when day-night confusion resolves, honest week-by-week timelines, and what actually helps.
Based on: Scott Rivkees, Barbara Galland, Ivo Iglowstein + more
8 min read · Updated April 2026
Sharing sleep care with daycare, grandparents, and sitters
How to share your baby's sleep plan with partners, grandparents, daycare, and sitters — what to communicate, why consistency matters, and how Happyly makes it easy.
Based on: Jodi Mindell, Avi Sadeh, Harriet Hiscock + more
7 min read · Updated April 2026
How to sleep train without cry-it-out: gentle methods that actually work
A research-backed guide to gentle sleep training. Graduated extinction, bedtime fading, camping out — what the evidence says, what to expect, and how to stay consistent.
Based on: Michael Gradisar, Harriet Hiscock, Jodi Mindell + more
8 min read · Updated April 2026
Toddler sleep regressions: 18 months and 2 years
A research-backed guide to toddler sleep regressions at 18 months and 2 years. Why they are different from infant regressions, what is driving them, and how to respond.
Based on: Anat Scher, Avi Sadeh, Jodi Mindell + more
7 min read · Updated April 2026
Baby wake windows by age: a complete guide (newborn to 24 months)
A complete, research-backed guide to baby wake windows by age. Newborn to 24 months: ranges, transitions, and how to tell over-tired from under-tired.
Based on: Marc Weissbluth, Barbara Galland, Ivo Iglowstein + more
10 min read · Updated April 2026