Reference

Baby Sleep Glossary

50 sleep terms every parent of a baby or toddler ends up Googling at some point. Plain-language definitions, no jargon. Search by keyword or filter by category.

51 terms

AAP Safe Sleep: American Academy of Pediatrics safe sleep recommendations: alone, on the back, in a crib with a firm flat surface and no loose objects. Updated most recently in 2022.
Back to Sleep: The AAP recommendation that infants always be placed on their backs for sleep until at least 12 months. Once a baby can roll both ways independently, you no longer need to roll her back.
Bassinet: A small sleep surface for newborns and young infants, typically used until 4-6 months or until baby can roll/push up. Must have a flat, firm sleep surface and meet current CPSC standards.
Bed-Sharing: Sleeping on the same surface as your baby. Not recommended by the AAP because of suffocation and SIDS risk, especially under 4 months.
Bedtime Routine: A short, predictable sequence of activities (bath, book, song, bed) repeated every night to cue your baby's body that sleep is coming. Strongly associated with easier bedtimes and better night sleep.
Catnap: A short nap, typically 30-45 minutes. Common in younger babies. Some catnaps are developmentally normal; others signal that the wake window was too long.
Chair Method: Also called the Sleep Lady Shuffle. Parents sit in a chair next to the crib at bedtime and gradually move the chair further away over 1-2 weeks. Good for parents who want to stay present. Developed by Kim West.
Circadian Rhythm: The body's internal day-night clock. Babies don't have a real circadian rhythm at birth; it develops around 8-12 weeks. Light exposure, feeding times, and bedtime routines help it form.
Crib Bumper: Padded liner around the inside of a crib. Banned in the U.S. as of 2022 (Safe Sleep for Babies Act) because of suffocation, entrapment, and strangulation risks. This includes mesh and 'breathable' versions.
Crib Hour: The practice of leaving baby in the crib for a full hour even if she wakes early from a nap, giving her a chance to fall back asleep. Effective for many babies in the 6-12 month range.
Cry It Out (Extinction): A sleep training method where parents place baby down drowsy but awake and do not return until morning (except for safety/feeding needs). Fastest results, hardest emotionally for parents. Not for babies under 4-6 months.
DreamGenius: Kiri's personalized sleep training program. Built with pediatric sleep specialist Courtney Palm, it adapts to your baby's actual data and your parenting style instead of prescribing one rigid method.
Drowsy But Awake: Placing baby in the crib while she's tired but not yet asleep, so she falls asleep in her own sleep space. The foundation of independent sleep skills.
Early Rising: Waking for the day before 6:00 AM (or earlier than you'd like). Causes include going to bed too late, going to bed too early, too much daytime sleep, light leaking into the room, or a wake window mismatch the prior evening.
Fading: Gradually reducing the support you provide at bedtime over weeks. Could mean shortening the rocking time, moving the rocking chair further from the crib, or fading out night feeds incrementally.
False Start: When a baby falls asleep at bedtime, wakes 30-60 minutes later, and is upset and hard to resettle. Usually means the last wake window was too short or bedtime was slightly off.
Ferber Method: Graduated extinction. Parents leave the room and return at progressively longer intervals (3, 5, 10 min) for brief comfort. Typically resolves in 3-7 nights. Developed by Richard Ferber, MD.
Inclined Sleeper: A sleep surface at an angle. Banned in the U.S. since 2019 (federal recall) because of fatal sleep risk. Babies should always sleep flat.
Nap Transition: The shift from one nap structure to another (e.g., 3-to-2 naps around 6-9 months, 2-to-1 naps around 13-18 months, dropping the nap entirely between 3-5 years).
Night Terror: A partial-arousal parasomnia common in preschoolers. The child appears terrified (screaming, thrashing, eyes open) but is not actually awake and won't remember it. Different from a nightmare.
Nightmare: A bad dream that wakes the child during REM sleep, usually in the second half of the night. The child is fully awake and often remembers it. Different from a night terror.
NREM Sleep: Non-Rapid Eye Movement sleep. The deeper, less-dreaming sleep stages. Night terrors and sleepwalking happen during NREM, usually in the first 1-3 hours of the night.
Obstructive Sleep Apnea (OSA): A condition where breathing repeatedly pauses during sleep, usually from enlarged tonsils or adenoids. Signs: snoring, gasping, pauses in breathing, mouth breathing, restless sleep. Warrants pediatric evaluation.
Overtired: Past the point of optimal sleep timing. Overtired babies produce cortisol, which makes settling harder and sleep more fragmented. Often counterintuitive: a baby fighting sleep is usually overtired, not undertired.
Pacifier: Sucking device for self-soothing. The AAP recommends offering a pacifier at sleep time (after breastfeeding is well established) because it's associated with reduced SIDS risk.
Partial Arousal: A brief, partial waking between sleep cycles. Adults have these too but don't usually notice. Babies who haven't learned independent sleep skills may fully wake during partial arousals.
Pick-Up-Put-Down: Gentle method where parents pick up baby when she cries, soothe briefly, and put her back down. Repeated as needed. Minimal crying, slower results. Popularized by Tracy Hogg.
Play Yard: A portable enclosed sleep space (formerly called a Pack 'n Play). Safe for sleep when set up flat with only the manufacturer's mattress pad and a fitted sheet.
Quiet Time: A structured rest period that replaces napping for older toddlers and preschoolers who no longer need a nap. Typically 30-60 minutes of calm independent play in a designated space.
REM Sleep: Rapid Eye Movement sleep. The stage when dreams happen. Babies spend much more time in REM than adults. Around 50% of sleep in the first weeks, dropping toward adult levels (~20%) over the first few years.
Room-Sharing: Baby sleeps in your room on her own sleep surface (crib, bassinet, or play yard) for at least the first 6 months. Recommended by the AAP. Different from bed-sharing.
Second Wind: A burst of frantic energy when the wake window has stretched too long. Often mistaken for 'she's still wide awake.' Usually followed by a hard crash 30-45 minutes later. A sign you missed the window.
Self-Soothing: The skill of falling asleep (or back asleep) without external help. Babies typically develop this capacity around 4-6 months, but it's also a learned skill, which is why sleep training works.
Short Nap: A nap under 45 minutes in babies over 4 months. Usually means the wake window was slightly too long. The fix is often putting the baby down sooner, not later.
SIDS: Sudden Infant Death Syndrome. The sudden, unexplained death of an infant under 12 months. Risk is reduced by following AAP safe sleep practices (back sleeping, firm flat surface, no loose bedding, room-sharing).
Sleep Architecture: The pattern and structure of sleep stages across a night. Baby sleep architecture matures around 4 months, which is the underlying cause of the 4-month sleep regression.
Sleep Cycle: A full pass through the sleep stages (NREM 1 → 2 → 3 → REM). In adults, ~90 minutes. In babies, ~45-60 minutes, which is why babies often wake or partially rouse on the hour or half-hour.
Sleep Onset: The transition from awake to asleep. The first few minutes after lights out are often the shortest, lightest stage of sleep. Easy to disrupt with noise or movement.
Sleep Pressure: The biological drive to sleep that builds up during wakefulness. Too little sleep pressure makes settling hard. Too much (overtiredness) also makes settling hard.
Sleep Regression: A temporary stretch (typically 2-6 weeks) when a previously good sleeper wakes more, fights sleep, or loses nap structure. Almost always tied to a developmental leap. Common at 3, 4, 8, 12, 18 months, and 2-3 years.
Sleep Sack: A wearable blanket that zips or snaps closed. Replaces loose blankets, which are unsafe in cribs. Available in different TOG ratings for different room temperatures.
Sleeping Through the Night: Definitions vary. Pediatric researchers typically use a 5-6 hour stretch as the threshold. Most healthy babies are capable of this by 6 months, though night feeds may persist for nutritional reasons.
Sleepwalking: A parasomnia where the child gets up and walks while not fully awake. Most common in preschoolers and school-age children. Keep the home safe (gates on stairs) and gently guide back to bed.
Sleepy Cues: Signs that your baby is ready for sleep: rubbing eyes, pulling ears, looking away, glazed stare, getting suddenly clingy or whiny. Cues often beat the clock for nap timing.
Split Night: A long wakeful stretch in the middle of the night, often 1-2 hours. Most common in babies who are getting too much daytime sleep, have very early bedtimes, or are in the middle of a sleep regression.
Swaddle: A snug wrap that mimics the womb and prevents the startle reflex. Safe for newborns until baby shows signs of rolling (around 2-4 months), at which point swaddling must stop immediately.
TOG Rating: Thermal Overall Grade. A measure of how warm a sleep sack is. Lower TOG (0.5) for warm rooms; higher TOG (2.5+) for cooler rooms.
Tummy Time: Supervised time spent on the stomach during awake periods. Builds neck strength and supports motor development. Always awake, always supervised, never during sleep.
Wake Time: The moment your baby's eyes open to start the day or end a nap. Wake windows are timed from this point, not from when feeding ends.
Wake Window: The amount of time your baby is awake between sleep periods. Wake windows lengthen with age. Matching the wake window to your baby's age is the single biggest lever for smoother naps and easier bedtimes.
Witching Hour: The late-afternoon-to-early-evening fussiness common in newborns (usually 4-7 PM). Tied to accumulated overtiredness, immature digestion, and circadian rhythm not yet formed. Resolves by 3-4 months.