LIVING NATURALLY with Olwen Anderson

THE longer you live, the more you can appreciate how good a solid sleep feels; after a restless, shallow sleep it's hard to enjoy the day. Your mood isn't as bright, you don't tolerate other people's quirky habits so easily, and your appetite for sugary food soars.

Before you look for the magic supplement to cure your unsatisfying sleep, consider the smart phone, tablet or computer you're using at night could be the culprit.

It's all about light and melatonin. During the day, light reaching your optic nerve sends information about what time of day it is to a tiny but powerful part of your brain, the supra- chiasmatic nucleus. This is our internal timekeeper that regulates when we sleep and wake. Lots of blue light coming in means it's daytime.

As the light of the day fades into evening less light hits your optic nerve, and the suprachiasmatic nucleus understands from this that you will be sleeping soon. So it instructs your pineal gland nearby to begin secreting melatonin, a hormone that prepares you for sleep and keeps you asleep. Then in the morning as light hits your eyes, melatonin declines.

As you age your body's ability to produce melatonin declines, and even without over-exposure to bright light at night you can begin to get the sense that you just don't sleep as well as you did when you were younger. Keep this in mind as we examine a new modern habit: using smart phones at night - because they emit that blue daytime-like light.

You might be sending texts, browsing the internet, playing games. While you're staring at that engaging screen, the blue light sends the wrong message through your optic nerve: that it's daytime. In response, your suprachiasmatic nucleus dispenses new instructions to halt the melatonin production, seems like it's daylight after all. Your body, confused, responds by trying to stay awake even though you're feeling tired. Without the help of melatonin your sleep just won't be really deep and refreshing.

If you suspect your screen use could be contributing to your own unsatisfying sleep, why not try imposing a screen curfew for a few weeks to see whether your sleep quality improves. That means not using your smart phone, tablet or computer for tasks like browsing the internet (where you're staring at the screen) after a certain time at night - perhaps two hours before you go to bed.

Olwen Anderson is a naturopath and counsellor. www.olwenanderson.com.au