The essential elements of human existence could be narrowed down to air, water and food. Deprived of any of these for any length of time and the human body will soon deteriorate. Luckily, for most people in western society at least, this isn't a problem as breathing is second nature and food and water are in abundance. But in terms of long-term physical and mental wellbeing, there is a fourth element that is as crucial as any of these: sleep.

For many, sleep seems to have fallen off the 'wellbeing radar'. As long as they get enough to be able to function the next day then that's fine. But research has shown that sleep-deprivation - or "sleep-debt" - suppresses the immune system and can contribute towards ill-health. This is, perhaps, why most doctors suggest getting plenty of rest as part of the recuperation process. Furthermore, oversleeping has also been shown to have consequences on long-term health. Studies have shown that people who, on average, sleep more than 10 hours or less than 4 hours per night, don't live as long as people who sleep the standard seven hours.

Of course, many would argue that getting the recommended seven hours per night is easier said than done, as the UK moves more towards a 24/7 society, with people working longer hours and shops, bars and restaurants opening later.

Subsequently, countless people wonder why they have difficulty getting a decent night's sleep. But there are numerous changes that can be made to sleeping habits that can vastly improve the chances of a good night's rest. Firstly, it's important to get the basics right and have a comfortable sleeping environment. The size of the bed is crucial, which is why many couples choose to upgrade to a king-size bed, to create more personal space.

The , too, are equally important. For example, using goose down or other naturally-filled duvets help to regulate body temperature, allowing the body to breathe in a way a synthetic quilt doesn't.

Furthermore, many people choose to sleep with a light or the television on, which only serves to keep the brain roused when the purpose is to wind-down and rest. And despite what everyone is told as a child, counting sheep only stimulates the "thinking organ" too.

Finally, the three hours before sleep is crucial; avoid drinking caffeine, eating heavy meals or doing any significant exercise. And importantly, only go to bed when tiredness has set in, otherwise any existing sleep anxiety is likely to be worsened. Coupled with a pitch-dark, comfortable and quiet sleeping-space, the chances of a deep and dreamy slumber will be vastly increased.

For morning people and night owls alike, sleep is an often overlooked aspect of physical and mental wellbeing, and it's easy to forget that the quality of sleep is as important as the quantity of sleep. So relax, unwind and turn the lights and television off!