Top tips for taking care of your eyes

The human body is a remarkable machine. But like any other machine, parts of it can break down. The eyes are a prime example. We don't consider them until something goes wrong. Everyday living can damage sight, but these steps will protect it.

The first thing to remember is that bright sunlight can harm your vision. It increases damage from free radical formation in the eye and long hours in direct sun can damage your eyes and contribute to cataracts and macular degeneration.

• Ultraviolet and blue light cause most damage over long periods, so it makes sense to put on a broad-brimmed hat and a pair of sunglasses, along with the sunscreen.
• Reflected light is equally dangerous. Humans evolved in an unreflective environment of earth and trees.
• Concrete pavements and modern buildings reflect far more light, making us more vulnerable to light damage. It's also important to protect your eyes when on sand, water or snow, which reflect very efficiently.
• While sunlight can cause damage, so can working long hours inside under fluorescent office lighting. We spend much of our daily lives under artificial light — which may contribute to short sight. This runs counter to our nature; human eyes evolved to spend daylight hours outdoors and nights in near-total darkness.
• Unlike our distant ancestors, who slept a lot longer during winter nights, we spend many hours of darkness under artificial light.

Often we sleep in rooms that let in outside light, which can adversely affect our eyes, as eyes need darkness to rest effectively. Natural light and darkness help to set our body clock.

• Any disruption, such as jet lag or shift work, can upset the rhythm. This is because the region in our brain that controls the timing of many biological functions — such as when we feel hungry or sleepy — is "set" by light-dark cycles.
• Until recently, scientists thought that the signals for these "circadian rhythms" came from the rods and cones of the retina.
• But recent research has shown that they are actually sent from another type of specialized cell in the retina — called a ganglion cell.
• These cells specifically detect sky-blue light, and "turn on" at about the same intensity as the daylight at dawn.
• Without this specific "switch on" signal, we are vulnerable to insomnia, fatigue and mood disturbances, including the winter depression known as SAD (seasonal affective disorder) that affects many people living in northern climates.
• The more contrast you can maintain between night and daylight levels, the better you sleep and the better it is for your eyes, it seems. If there's a streetlight outside your bedroom window, hang thicker curtains or black-out blinds.
• During daylight hours, spend more time outdoors. Go outside on weekends as well, and position furniture in the house so that you get more natural daylight in the places where you spend most time.