The Science of Baby Sleep Cycles: What’s Normal in the First Year
If your baby’s sleep feels unpredictable - short naps, frequent night wakes - you’re not doing anything wrong. Baby sleep is biologically different from adult sleep, and understanding how it works can ease a lot of stress.
Understanding the Mystery of Baby Sleep
If your baby’s sleep feels unpredictable - short naps, frequent night wakes - you’re not doing anything wrong. Baby sleep is biologically different from adult sleep, and understanding how it works can ease a lot of stress. Let’s look at what’s happening inside those tiny brains (and why tracking sleep with tools like Cuddlydoo can help you spot healthy patterns).
1. What Baby Sleep Cycles Look Like
Newborns sleep in short, irregular cycles-lasting about 45-60 minutes, compared to an adult’s 90-minute cycle. Each cycle has two main phases:
Active (REM) Sleep: Babies may twitch, grunt, or move their eyes beneath the lids. This phase supports brain development and learning.
Quiet (non-REM) Sleep: Breathing slows, and movements stop. This phase helps with physical growth and recovery.
According to the American Academy of Pediatrics (AAP), babies spend up to 50% of their sleep in REM in the early months—much more than adults, whose REM is about 20–25%. (AAP, 2022)
2. How Sleep Patterns Evolve Over the First Year
0-3 months:
14–17 hours per 24 hours (including naps)
Sleep is spread out with frequent waking for feeds
Day/night confusion is common (their internal clock is still developing)
3-6 months:
Cycles begin to lengthen
A more distinct day-night rhythm appears
Some babies begin to sleep longer stretches at night
6-12 months:
Total sleep: around 12–16 hours per 24 hours
Two naps are common
Night waking for comfort or developmental changes (like teething or new milestones) is still normal
(Source: CDC & NHS Sleep Guidance, 2023–2024)
3. Why Sleep Feels “Off” Sometimes
Babies don’t just sleep—they practice growing in their sleep. Developmental leaps (rolling, crawling, talking) can temporarily disrupt rest. Illness, changes in routine, or big transitions (like weaning or moving rooms) can also cause short-term regressions.
Try not to see it as “bad sleep”—it’s a sign their bodies and brains are evolving.
4. Supporting Healthy Sleep Rhythms
Track patterns: Apps like Cuddlydoo help you notice trends—average nap length, night waking frequency, and changes over time. Create a bedtime routine: Gentle cues like dim lights, quiet sounds, and consistent timing help signal sleep. Encourage day-night differences: More light and activity during the day, calm and dim in the evening. Practice safe sleep: Always place your baby on their back, on a firm, flat sleep surface, in a smoke-free room
(AAP, Safe Sleep Guidelines).
5. What’s “Normal”?
Normal sleep doesn’t mean “sleeping through the night.” For infants, it means steadily developing longer, more predictable stretches, with some ups and downs. Every baby’s rhythm is unique—especially in the first year.
Bottom line: Understanding sleep cycles keeps expectations realistic—and gives you confidence to support your baby’s growth without comparing or stressing. With gentle routines and helpful tools like Cuddlydoo, you can track progress, celebrate milestones, and rest a little easier.
Not medical advice. Consult your pediatrician for personalized guidance.
Sources:
American Academy of Pediatrics – HealthyChildren.org
Centers for Disease Control and Prevention (CDC) – Infant Sleep & Health
National Health Service (NHS) – How Much Sleep Do Babies Need?
World Health Organization (WHO) – Infant and Young Child Feeding and Sleep Recommendation
