I DON'T like the dark mornings and short days of mid-winter, so I am always glad when the winter solstice, or shortest day of the year, is over and we can look forward to the days getting longer in the new year.

The ancients held major festivals on the winter solstice and counted the days from then on to give them a guide as to when to sow their crops. Little wonder they built monuments like Stonehenge to determine the solstices of the sun and moon.

Sunshine is vital for our health and that of many animals as it plays an important role in the production of vitamin D, which helps calcium and phosphorous to be deposited in bones. A lack of that important vitamin leads to rickets and can be a problem in children and young animals during winter.

Research has suggested that Scotland's high incidence of multiple sclerosis could be down to a shortage of sunlight in the winter, and there is an argument for us to take a vitamin D supplement to prevent the condition developing.

Many farmers, like other folk, often respond well to increasing amounts of daylight. Seasonal affective disorder (SAD), or winter depression, is a well-known medical condition caused by a shortage of light.

Sunlight is so essential to most life on earth that the bible teaches us that it was the first thing to be created.

Sunlight and water are the two main ingredients for successful farming. Indeed you don't even need land to grow crops, as that can be done by hydroponics.

Photosynthesis, that wonderful chemistry that enables plants to store the sun's energy as starch, is the foundation of most food chains. Plankton in the sea, grass, grain and all other crops on land are created by the marvel of life-sustaining photosynthesis. The sun is literally a creator of life and as a result was worshipped by many ancient societies.

While Scotland is a dark and dreary place in the dead of winter, it makes up for it by having long hours of daylight in summer. That allows us to grow heavier crops of brassicas like turnips and oilseed rape compared with England and Wales.

Daylight also has a significant effect on farm animals. Sheep come into season in the autumn in response to shortening daylight, so that they will lamb in the spring when the weather is kinder and grass beginning to grow again.

Some farmers used to manipulate the amount of light available to their ewes to encourage them to breed out of season. They put them indoors where they could shut out the daylight and fool them into thinking the days were getting shorter so they would come into season. That way they lambed during the winter to produce prime lambs that were ready for the lucrative Easter trade.

Wool grows fastest on the longest day of the year to guarantee sheep a heavy fleece to cope with the cold blasts of late autumn and early winter.

Light also plays a big role in the life cycles of birds that lay their eggs in the spring in response to lengthening daylight so their chicks will hatch out in warmer weather when there are more insects to feed on.

Poultry farmers increase the amount of artificial light in their henhouses during the winter months to fool their hens into thinking the days are longer than they really are and that spring is on the way. That encourages them to lay more eggs.

Cattle don't really start to thrive until the turn of the year. That is partly due to the fact it takes some time to adjust to being brought indoors in the autumn and adjusting to the change of diet from grass to winter rations - but the main reason is that as the amount of daylight increases, so does their appetite. It's the increased daily intake of feed that prompts them to grow faster and put on more weight.

Even the light of the moon influences the appetite of farm animals. Research has shown that cattle can eat 10 to 12 per cent more when there is a full moon.

Light is so important in livestock farming that many farmers increase the amount of artificial light in their sheds during the winter. Not only do beef cattle put on more weight in response to the increased light, but many dairy farmers believe it also helps to increase milk yields.

Intensive livestock farmers even dim the artificial lights in their pig and poultry sheds to reduce aggression among the occupants.