Expert sleep guides blog, science-backed tips & in-depth articles. Improve your sleep quality, fix insomnia, and wake up refreshed — free at SmartSleepCalc.com
Deep Sleep Science Deep Sleep (N3) by Age: The Ohayon Normative Data Guide N3 slow-wave deep sleep declines by approximately 2% per decade of adult life — from around 24% in childhood to under 5% in adults over 70. This page presents the Ohayon et al. (2004) normative data as the definitive reference for what…
REM Sleep Science REM Sleep by Age: From Newborn to Senior REM sleep changes more dramatically across the human lifespan than any other sleep stage. From 50% of total sleep in newborns to 15–18% in older adults, this trajectory tells the story of brain development, cognitive maintenance, and what is normal at every age. The…
Toddler Sleep Guide Toddler Sleep: Ages 1-5 From the 18-month regression to the nap drop, toddler sleep is one of the most challenging — and most misunderstood — phases. The nap transition readiness checker, sleep regression guide, and night terrors explainer are designed to give parents accurate, evidence-based guidance without the anxiety. Nap Transition Checker…
🔒 AAP Safe Sleep Guidelines (2022 Update)American Academy of Pediatrics — evidence-based recommendations to reduce infant sleep-related deaths Always ✓Place baby on their back to sleep — every sleep, every time, until age 1 ✓Use a firm, flat, non-inclined sleep surface — approved crib, bassinet, or play yard with a firm mattress and fitted sheet…
Adolescent Sleep Biology Teenager Sleep: Biology, Not Behaviour Teenagers staying up until midnight and being unable to wake at 6:30am is not laziness or a lack of discipline. It is a documented hormonal shift that affects every adolescent across all cultures. Understanding the biology changes the conversation. The core fact: at puberty, melatonin onset shifts…
Best Time to Sleep – Personalised by Chronotype The Best Time to SleepIsn’t 10pm for Everyone – It’s Your Biological Night Instead of a generic “10pm bedtime,” this page uses your required wake time and chronotype to estimate your optimal bedtime range, anchored in dim-light melatonin onset (DLMO) – the circadian signal that actually defines…
Excessive Napping — Health-Aware Guide Am I Napping Too Much?Normal Napping vs When to See a Doctor Daily napping is healthy for most adults — but irresistible daytime sleepiness despite adequate night sleep is a different situation that can have a medical cause. This guide helps you tell the difference. SmartSleepCalc • YMYL health-adjacent •…
90-Minute Nap — Full Sleep Cycle Science The 90-Minute Nap:One Complete Sleep Cycle. Less Grogginess Than 60 Minutes. Counterintuitive but true: a 90-minute nap produces less grogginess than a 60-minute nap. It is also the only nap duration that provides both N3 deep sleep and REM sleep — and it uses the identical cycle logic…
60-Minute Nap — Honest Situational Guide The 60-Minute Nap:Who Needs It, Who Doesn’t & How to Recover A 60-minute nap is rarely the right choice. It is not a longer power nap — it is a different tool entirely, with genuine N3 deep sleep benefits, significant grogginess risk, and a very specific set of situations…
15-Minute Nap — Start Timer Now The 15-Minute Nap:Built-In Timer, Fast-Sleep Techniques & Science For fast sleepers only. Start the countdown immediately, learn how to fall asleep in under 5 minutes, and understand exactly what your brain does in 15 minutes — and whether this nap is even right for you. SmartSleepCalc • Tietzel &…
