The first weeks of daycare often bring a noticeable dip in a baby's sleep, and understanding the genuine biology behind this adjustment period helps parents respond with patience rather than worry that something has gone wrong.
A Real, Measurable Stress Response
Research on the transition to childcare has documented elevated cortisol levels in infants and toddlers adjusting to a new daycare environment, with one line of research finding that children even show anticipatory stress the night before a daycare day, resulting in elevated overnight cortisol activity. A meta-analysis reviewing multiple studies confirmed this pattern of elevated cortisol during daycare adjustment is genuinely consistent across the research literature, though the response typically eases as a child settles into the new routine over time.
How Fragmented Sleep and Stress Reinforce Each Other
Research measuring toddlers in group childcare settings found that children with more fragmented sleep showed higher morning cortisol levels, illustrating a genuine two way relationship where the stress of transition can disrupt sleep, and disrupted sleep can in turn heighten stress reactivity the following day. This cycle helps explain why the roughest sleep often appears in the first one to two weeks of a new daycare routine, before both the stress response and sleep pattern have had time to stabilize.
The Caregiver Relationship Makes a Genuine Difference
Research on attachment and childcare has found that babies and toddlers navigate non-parental care considerably more smoothly when they develop a consistent secondary attachment bond with one reliably present caregiver at the facility. Separate research on daycare environments found children showed healthier, more naturally declining cortisol patterns throughout the day in centers where caregivers were consistently sensitive and responsive to each child's individual needs, underscoring how much the quality of care itself shapes the adjustment experience.
Supporting Sleep During the Transition
- Expect the roughest stretch to fall within the first one to two weeks, with gradual improvement as your baby builds familiarity and trust with new caregivers
- Keep home routines as consistent as possible during this period, since predictability at bedtime offers a stabilizing counterweight to the new daytime environment
- Communicate closely with daycare staff about your baby's sleep needs and typical soothing preferences, since a caregiver aware of your baby's cues can ease the daytime stress that carries into nighttime sleep
- Allow extra patience for night waking or clinginess during this window, treating it as a temporary and genuinely normal part of adjustment rather than a regression to address urgently
The takeaway: A dip in sleep quality when starting daycare reflects a real, measurable stress response rather than a sign that something is fundamentally wrong, and this typically resolves naturally as your baby builds trust and familiarity with their new routine.