Baby Sleep Cycles

Sleep has become its own subspecialty in the field of medicine. Due to a large amount of research that has been done recently in the science of sleep, care providers can do extra training to work as sub-specialists in clinics dedicated to helping people with sleep problems. The most recent Nobel Prize in medicine was given to three researchers who studied sleep and its relationship to autoimmune diseases like diabetes, hepatitis, and mental health disorders.

We have known about the negative outcomes of poor sleep habits for a long time. Everyone has experienced feeling lethargic without enough sleep which leads to poor performance and learning during the day. Many hormone levels get disrupted when there is a sub-optimal amount of sleep. Growth hormone levels are decreased while the thyroid hormone is increased. Cortisol levels are correlated with sleep patterns and it is unhealthy to have abnormal levels of cortisol during the day. Sleep deprivation was even used as a form of torture!

In the past, sleep was considered a “passive, dormant” process where our brains rested. Far from dormant, sleep is a dynamic process that affects both young and old alike.  Now, let’s dig into the four stages of sleep.

Stage 1

This stage of sleep is the “light sleep” phase where we drift in and out of sleep and can be awakened easily.  It is normal for babies to wake up several times during a typical night.  Babies who wake up after having been lulled to sleep will usually wake up fussing, confused and frightened.

Stage 2

During this stage of sleep, our brain waves and our eye movements start to quiet down.

Stages 3 and 4

The final stages are the deep sleep stages. It is difficult to wake someone up during these last 2 phases. Some children experience night terrors (episodes of screaming, flailing and fear whiles asleep which they don’t remember) during stages 3 and 4.  When we fall into REM sleep our eyes move rapidly and muscles feel paralyzed. This is the phase where we dream. Adults spend half of their sleep cycle in REM sleep where babies spend half of their sleep cycle in Stage 2.

As parents and caregivers, it is important to understand that babies require adequate amounts of sleep to achieve proper growth and development. Negative sleep patterns (lack of good quality sleep) can lead to negative behaviors (cranky and irritated kids). Caregivers can be instrumental in helping families create healthy sleep habits for their children. So … how do we get rid of these negative sleep patterns?

Negative sleep patterns can be reversed with minor behavioral strategies. However, the older the child is the harder it is to make the changes. There are two main “drives” that affect how alert or sleepy we are. The first is our “sleep deficit” which is how much sleep we are actually getting compared to how much we need (external clock). Our sleep deficit increases the longer we go without sleep.

The second is our “circadian rhythm” which is our internal clock. Our circadian rhythms reflect the patterns of our sleep over a 24 hour period. Human beings are programmed to sleep when it’s dark and to be awake when it is light out, although this pattern can be changed depending on the desired schedule. Our circadian rhythm turns on around our usual bedtime, is the strongest in the middle of our sleep and shuts off when we wake up. It is easiest to fall asleep when our two sleep drives (sleep deficit and circadian rhythm) are aligned. For example, if we have decreased our sleep debt because we napped during the day, falling asleep at night will be more difficult.  Holding off on sleep despite being tired means that we are not aligning our internal and external clocks.  It is more difficult to sleep when your circadian rhythm is off. Understanding the relationship between our external (sleep deficit) and internal (circadian rhythm) can help parents and caregivers to create their baby’s sleep schedule.

According to the American Academy of Pediatrics, the average amount of sleep in a 24 hour period for each age group on a regular basis promote optimal health is:

Newborns 16-18 hours

1-3 months 15-16 hours

3-6 months 14-15 hours

6-9 months 13-14 hours

9-12 months 12-14 hours

1-2 years 11-14 hours

3 to 5 years 10-13 hours

6 to 12 years 9-12 hours

13 to 18 years: 8-10 hours per 24 hour

To learn more about infant sleep cycles please visit