18 month sleep regression

Around 18 months many toddlers start refusing naps, fighting bedtime or waking at night. Here is what is known about why and what you can do.

Is there an 18 month sleep regression?

Sleep regression is a popular name for a stretch of worse sleep in a baby who was sleeping better before. It is not an event that research has pinned to the calendar: Cleveland Clinic notes that research has not shown regressions happening like clockwork at a specific age for every baby.

The Sleep Foundation lists 18 months among the ages when a regression is not uncommon. No medical source describes it as a separate, predictable event.

What often unsettles sleep at 18 months

• The move from two naps to one. By 18 months most toddlers have given up the morning nap and take one long afternoon nap of 1.5 to 3 hours (Nationwide Children's Hospital).
• Teething pain or an illness. Nemours lists both among the causes of night waking at 1 to 2 years.
• Screens. Nemours advises no screens in the hour before bed and none in the bedroom.

How long does the 18 month sleep regression last?

Cleveland Clinic says regressions typically last a week or two. The Sleep Foundation says that in most cases the trouble lasts a few days to a few weeks. Nobody can give you a date, and it is different for every child.

What to do

• Rule out other causes first. Illness and teething can look the same.
• Keep the same bedtime routine every night, in the same order. In a study of 405 children of 7 to 36 months, a consistent routine improved how fast they fell asleep and how often they woke.
• Keep offering the nap at the same time every day, even if it is refused for a few days.
• Keep wake-up time and bedtime at about the same times every day.
• Answer night wakings the same calm way every night.

Can you sleep train an 18 month old?

Yes, if you want to. The same approaches are used with toddlers: staying in the room and moving away over two weeks, timed checks (the Ferber method), and saying goodnight and not going back in (cry it out). A toddler in a bed they can leave needs a version with check-ins.

A 2006 review for the American Academy of Sleep Medicine found that 49 of 52 studies reported better sleep. Most of those studies were small, and no method works for every child.

When to call the pediatrician

Talk to your pediatrician if sleep does not get back on track, if something does not seem right to you, or if you notice snoring, trouble breathing, a fever, poor weight gain or feeds that are a struggle.

Related guides

• 18 month old sleep schedule
• Sleep regression ages
• The Ferber method and chart

Sources

• Cleveland Clinic. The 4-Month Sleep Regression: What Parents Need To Know. July 2022.
• Sleep Foundation. 4-Month Sleep Regression. Updated July 2025.
• Nemours KidsHealth. Sleep and Your Baby, by age; Naps.
• Nationwide Children's Hospital. Sleep in Infants; Sleep in Toddlers.
• Mindell JA, et al. Behavioral treatment of bedtime problems and night wakings in infants and young children. Sleep, 2006 (review for the American Academy of Sleep Medicine).

General information for parents, not medical advice. Independent, not affiliated with the American Academy of Pediatrics or any medical body. Talk to your pediatrician about your baby's health.