Our circadian rhythm helps us with being awake by day and asleep at night and follows a roughly 24-hour cycle responding primarily to light and darkness in our environment.
Our bodies start producing more cortisol around 4am-5am preparing us to wake up. Cortisol is a stress hormone that our bodies need to be awake but also for fight or flight situations or when our blood glucose is low.
Our cortisol levels dip a few times during the day, usually mid-morning and again late afternoon. No, it isn’t always that big lunch making you feel drowsy!
Cortisol levels dip again after dinner; that’s why we usually feel sleepy as we settle in on the sofa.

Darkness and light play very important roles in regulating melatonin production. Our bodies secrete melatonin when the sun sets at night and it keeps increasing until we go to bed.
Artificial light like bright lights, television screens, I-pad and mobile phone screens interfere with our body’s production of melatonin. (Blue light blockers are widely available and could help adults who can’t give up their screen time)

Most babies take 12 weeks to develop their circadian rhythms. While the baby is in utero the mother’s melatonin is passed across the placenta and helps the baby with a day-night routine together with his mom’s routine that he senses. At birth, this hormonal bond is broken and the baby has to struggle by himself to establish a routine.
Studies suggest that babies exposed to natural lighting patterns (brighter during the day and dark at night) adapted to the 24hour cycle quicker than those exposed to constant low levels of light. Babies getting outdoors often developed stronger circadian rhythms as a result.

Long days and irregular bedtimes can disrupt our circadian rhythms and it is therefore very important to keep a regular sleep and wake schedule with enough time allowed for quality sleep. Routine is especially important for babies.  Do not overtire your child thinking that they’ll sleep better or longer during the night.
It can be helpful to make bedrooms as dark as possible to prevent early morning light from waking you up too early. Avoid bright lights and screen time for an hour or more before bedtime.