It has been noticed that children who get to live the bulk of their days outdoors; when the full hours of daylight are physically experienced bodily - become children whose day/night body clocks are synced and naturalised. These children seem more able to sink into their sleep hours more readily.
'The circadian biological clock is controlled by a part of the brain called the Suprachiasmatic Nucleus (SCN), a group of cells in the hypothalamus that respond to light and dark signals. From the optic nerve of the eye, light travels to the SCN, signalling the internal clock that it is time to be awake. The SCN signals to other parts of the brain that control hormones, body temperature and other functions that play a role in making us feel sleepy or awake.
Your circadian rhythm is basically a 24-hour internal clock that is running in the background of your brain and cycles between sleepiness and alertness at regular intervals. It's also known as your sleep/wake cycle.
A part of your hypothalamus (a portion of your brain) controls your circadian rhythm. That said, outside factors like lightness and darkness can also impact it. When it’s dark at night, your eyes send a signal to the hypothalamus that it’s time to feel tired.'
Going from outdoors in to indoors, for a child or adult who spend their day in natural daylight can be enough of a trigger to induce melatonin production.
'In the mornings, with exposure to light, the SCN sends signals to raise body temperature and produce hormones like cortisol. The SCN also responds to light by delaying the release of other hormones like melatonin, which is associated with sleep onset and is produced when the eyes signal to the SCN that it is dark. Melatonin levels rise in the evening and stay elevated throughout the night, promoting sleep...'
To optimise the natural circadian clock, 'it can help to keep the lights dim at night as bedtime approaches. It can also help to get into bright light as soon as possible in the morning.' (sleepfoundation.org)
..... and to spend your days outdoors experiencing the full spectrum of daylight hours.
Nurture Outdoor Kindergarten: Here to fulfil every small person’s quota of daily daylight and facilitator of great sleep!