Sleep is so complex, especially a baby’s so let’s break it down so you can understand your child’s sleep better.
Our sleep and wake cycles are controlled by our circadian rhythm. This is everyone’s unique 24-hour internal clock. When it is dark, our eyes send signals to our brain to release the hormone melatonin. Melatonin makes us sleepy and helps us fall asleep. As morning time approaches and the sun comes out our bodies produce less melatonin. A hormone called cortisol is released which helps signal us to wake up and be alert. Therefore, the circadian rhythm is directly correlated to daytime (light) and nighttime (dark).
Our circadian rhythm is something that develops over time. Therefore, newborns who have never been exposed to light prior to being born have a very underdeveloped circadian rhythm. A baby’s circadian rhythm slowly starts to develop around 6 weeks of age. This is why in the early weeks a baby will sleep all day and be up all night. They simply cannot tell the difference which is known as day/night confusion.
Once a baby reaches 6 weeks of age and is able to differentiate between day and night it is a good idea to start implementing a bedtime routine. Having a consistent, relaxing bedtime routine will help your baby to understand that the day has ended, it is now night, and this means it is time to sleep. It is also very important to avoid all electronics (television, computer, tablet, etc.) and dim the lights 1 hour before bedtime. Putting your baby to bed and waking them around the same time every day also helps to regulate their circadian rhythm.
Around 4 months of age a baby undergoes a permanent change in the way they sleep. This is often referred to as the 4 months sleep regression. Until about 4 months of age, babies do not sleep in cycles. They go from light sleep to deep sleep and can remain there anywhere from 30 minutes to a few hours. This makes newborn sleep very unpredictable and irregular. Once a baby starts to sleep in cycles like adults, they go through the 5 sleep stages which are divided into 2 types of sleep.
- REM (Rapid Eye Movement)
- Non-REM
The 5 stages of sleep are as follows:
- Stage 1: Very light sleep (Non-REM): In this stage of sleep the eyes get very heavy and start closing. Baby starts to doze off.
- Stage 2: Light sleep (Non-REM): Sleep begins but a baby can startle very easily.
- Stage 3: Deep sleep (Non-REM): Deep sleep begins. If woken up baby would be very confused and groggy.
- Stage 4: Deepest sleep (Non-REM): This is the most restorative stage of sleep. It is very difficult to wake a baby from this stage of sleep.
- Stage 5: REM sleep: Sleep is light, but active. This is when dreaming occurs.
When going through the 5 stages of sleep, babies, and adults too for that matter do not always go in order. For example, a baby can go from stage 1, then 2, 3, 4, back to 3, 2 then 5. After stage 5 the cycle starts again at stage 1 which is very light sleep. This is when a baby will partially or fully wake. If a baby does not know how to fall asleep on their own and was put to bed asleep after being rocked for example, they will not be able to transition between sleep cycles. This results in frequent night wakings and short naps which requires parents to put them back to sleep the same way they fell asleep initially.
We go through many sleep cycles throughout the night, each lasting anywhere from 45 to 90 minutes. Sleep in the beginning of the night is the deepest and most restorative. This is when melatonin levels are at their highest. As the night goes on and we move into the early morning sleep gets more superficial and less deep making it easier to get woken up. This is when early morning wakings can become problematic and more frequent especially if a baby does not know how to put themselves back to sleep.
Since sleep is the deepest and most restorative in the beginning of the night an early age-appropriate bedtime for babies and young children is extremely important. This is when their brains process the new skills they have learned, their memory develops, their immune system strengthens and they grow, just to name a few of the important health benefits of sleep for your child.
If you are having trouble with your baby, toddler or preschoolers sleep and want to work 1-on-1 with me, check out my sleep programs or book a free call.
