Understanding Newborn Sleep Cycles: A Guide for New Parents

If you search for any information on infant sleep, you are likely to see ‘sleep cycles’ mentioned. But what are sleep cycles, and how do they impact sleep? Let’s explore this topic in depth.

Humans experience different stages of sleep, which range from deep to light sleep. It’s thought that sleep cycles serve a protective function. Historically, our ancestors were more vulnerable to threats, like wild animals, while they slept. The need to balance rest and safety likely led to the evolution of sleep cycles.

• Deep sleep allows for restorative rest, cell renewal, and memory consolidation. However, it makes us harder to rouse, potentially leaving us vulnerable.
• Light sleep offers less restorative benefits but makes us more alert to environmental dangers.

The balance of deep and light sleep creates a pattern called the sleep cycle. This helps us maintain safety while still getting the benefits of sleep.

As humans grow, their sleep cycles evolve. Newborns have different sleep patterns than older babies, children, and adults.

• Newborn Sleep (0–16 weeks): Newborns have two stages of sleep: light (REM) and deep. During REM sleep, newborns often exhibit little eye movements. Since newborns are easier to wake during REM sleep, it’s helpful to wait 15 minutes after they fall asleep before transferring them to their sleep space.
• 4 Months Onward: Around 16 weeks, babies develop four sleep stages: three non-REM stages (NREM) and one REM stage. The change to four stages can cause more frequent night wakings and shorter naps, often referred to as the "4-month sleep regression." However, this is actually a progression in their sleep development, rather than a regression.

Yes, sleep cycles can vary based on the time of day. Babies may wake between cycles at night, but some can return to sleep without adult intervention.

• Newborns: Sleep is evenly spread between day and night, as they haven’t yet developed their circadian rhythm.
• 3–4 Months: Around this age, babies begin to experience their deepest sleep earlier in the night, around 7–11 pm, due to higher melatonin levels.
• 11/12 pm Onward: Babies enter lighter REM sleep after midnight, making them more likely to wake between cycles.
• Daytime Sleep: Daytime naps tend to be lighter, influenced by the hormone cortisol, which keeps babies more alert during the day.

The length of sleep cycles will increase as a child grows, with cycles becoming longer as they develop.

Sleep cycles are just one factor in understanding baby sleep. Other influences include:

• Sleep Pressure: This brain chemical builds during wakefulness and decreases during sleep. High sleep pressure can result in overtiredness, while low sleep pressure can lead to under tiredness.
• Individual Sleep Needs: Every baby has unique sleep requirements.
• Time of Waking/Bedtime: Sleep timing impacts quality.
• Age and Development: As babies grow, their needs evolve.
• External Factors: Environment, premature birth, exposure to light, diet, stimulation, exercise, pain, and illness all play a role in baby sleep.

The Predictive Sleep feature ensures that parents can be responsive to their baby’s unique sleep needs, rather than relying on generic schedules. It tracks sleep through Owlet's technology, providing a personalised approach backed by science and development research.

By using this feature, parents can gain insight into their baby's sleep cues, making bedtime more predictable and aligned with their baby's natural rhythms.