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The 8-Month Sleep Regression: Separation Anxiety and New Skills

Quick answer

Why does sleep get harder again around 8 months?

The 8-month window commonly overlaps with separation anxiety (babies now understand you still exist when out of sight, which can make bedtime harder) and new gross-motor skills like crawling or pulling to stand, which babies sometimes practice involuntarily in the crib. Neither is a medical problem; both are typical developmental milestones.

Last reviewed 2026-08-28 by Sleep Training Planner editorial team

If your baby was sleeping reasonably well and suddenly starts protesting bedtime or waking more around 8 months, two ordinary developmental threads are the most commonly cited explanations, and neither one is a sign that something is wrong.

Separation anxiety

Around this age, babies develop object permanence: the understanding that you still exist even when they can’t see you. That’s a cognitive milestone, but it has a sleep side effect. Being placed in a crib alone can newly register as “my parent is gone,” which older, more object-permanence-naive babies didn’t experience the same way. This tends to show up as harder bedtime goodbyes and more protest at a 2am waking than a 4-month-old typically shows.

New gross-motor skills

Crawling, pulling to stand, and cruising along furniture often cluster around this window too. Babies sometimes practice a brand-new skill involuntarily in the crib, including pulling to standing in their sleep and not yet knowing how to get back down, which can turn a normal brief night waking into a fully awake, upset baby stuck standing at the rail.

If you already have a sleep training plan in place

If your baby was sleep trained earlier and is regressing now, most guidance is to hold your existing plan rather than starting over from scratch, while being realistic that a few harder nights are common during this window. If your baby pulls to standing and gets stuck, it’s fine to help them back down calmly and then resume your plan; that’s a physical-skill assist, not the plan breaking down. If you haven’t started sleep training yet and are considering it now, the method-fit quiz still applies at 8 months; nothing about this age window changes which method might fit, though a baby actively practicing standing may do better with a chair-method or bedtime-fading approach that keeps crib time lower-intensity while the new skill settles. See the full method comparison for how each approach handles standing/climbing.

This page is educational, not medical advice. Talk to your pediatrician about your specific baby’s development and sleep. See our methodology for how this site is sourced and reviewed.