Sleep cycles.
A typical chart displaying how your child moves in and out of sleep cycles throughout the night! Light sleep also known as REM sleep is the stage where your children are asleep, yet their brain is as active, as if they were awake. This is the stage where if you try to creep out of the room, or put them down from sleeping in your arms, they are likely to wake up. They also dream in this stage of sleep and you may notice their eyes are flickering under their eye lids and they may twitch their arms or legs. It generally takes about 20 mins for your child to move into the next stage of sleep which is known as the Deep sleep -NREM stage. This is the deepest, most restorative sleep and is broken into 4 stages, each one more deeper and restful then the one before! Your child will sleep more soundly as their brain activity quietens and they will breath more steadily and quietly whilst their movements are slower and more fluent(due to the fact that they are no longer in a paralysed state, (like in REM sleep, to keep them safe when dreaming and twitching) it is in this stage that they are less likely to wake up when transferred or when you choose to exit the room! These sleep cycles are known as the bodies natural Circadian rhythm. They begin to emerge around 6 weeks of age, but are completely developed by 4-6 months. This is usually the culprit for cat napping and frequent night waking's. It is important to create some healthy and positive sleep associations before these develop, so that your child can utilise them in between sleep cycles and potentially transition from one to the next without to much fuss and waking.
