But, sleep is tremendously important for us. We are in need of sleep as much as we are oxygen.

Sleep is capable of working wonders - it increases one's work efficiency, extends one's lifespan and cures illnesses.

But, above all, it is when our body repairs the half a billion cells we lose each day.

On average, adults need between seven to nine hours sleep to feel refreshed and energised. Some people need more than this, while others may need less. As we get older, we tend to require less sleep, but every individual is different.

Sleep is a dynamic process. There are two distinct states that alternate in cycles and each state is characterised by a different type of brain wave activity.

Sleep consists of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. NREM is further subdivided into the following four stages:

Stage I (light sleep)

Stage II

Stage III & IV (deep sleep)

The stages of NREM sleep and REM sleep cycle four or five times during a night's sleep. Stages I, II, III and IV are followed by REM sleep. A complete sleep cycle, from the beginning of Stage I to the end of REM sleep, usually takes about 90 minutes.

Stage I of NREM is light sleep. This is usually when we are half asleep and easily wakened.

Stage II represents a large percentage of total sleep time and it is when the heart rate and the breathing pattern slow down.

In Stages III and IV, we enter a deep sleep where, if wakened, we feel disorientated and 'groggy'. Some children experience bedwetting, nightmares or sleepwalking during deep sleep. This is also when the immune system is at its most active.

REM sleep follows NREM sleep and is usually associated with dreaming. It represents a quarter of the total sleep time.

During REM sleep, our brain is very active, our muscles are very relaxed and our eyes move quickly from side to side.

A person usually has about four or five periods of REM sleep a night, dreaming more as they get toward the morning.

The first REM period of the night may be less than 10 minutes in duration, while the last may exceed 60 minutes.

When a person is extremely sleepy, the duration of each bout of REM sleep is very short, or it may be absent. During slow brainwave sleep, the body is resting and repairing itself, and REM sleep is believed to be essential for mental aspects of our health.

Sleep deprivation can be very serious, causing emotional disturbances in people. It may lead to aggressiveness or apathy, resulting in fluctuations between euphoria and depression and vice versa.

One can experience pain in joints, hallucinations and visions. People can lose their ability to think straight and act quickly. People sleep-deprived for long periods find it difficult to finish a sentence, remember things or find an appropriate word to describe something.

Sleep problems can affect every age group and one in three people in the UK now have a serious insomnia problem.

In most cases, there is no real problem and sleep problems are often caused by worry or excitement, for example, but other factors including lifestyle, illness, diet and the environment should be taken into consideration.

One of the main symptoms of Chronic Fatigue Syndrome (CFS), also known as ME, is fatigue. This long-term tiredness, that does not go away with sleep or rest, affects daily life - mentally and physically. Some people describe it as "overwhelming".

And sleeping well is tough when you're in pain, where both the pain and pain medications can disturb sleep.

People with the inflammatory condition Fibromyalgia often suffer from extreme tiredness. This varies in each individual, ranging from a mild, tired feeling, to the exhaustion of a flu-like illness. They often wake up tired, even though they have had plenty of sleep, which can make it difficult to do everyday things.

Sleeping tablets can provide relief, but they do not treat the cause of sleeplessness. This medication simply puts you into a state of unconsciousness, which is almost like sleep, but without its full restorative properties. They also come with side effects including drowsiness, memory loss and disruption of essential 'sleep' levels.

These highly-addictive drugs should only be used as a short- term solution, but are often prescribed to patients for years.

Studies have shown that a new food supplement, Asphalia, contains low doses of melatonin which helps to maintain a healthy sleep and results in the user reaching REM sleep faster than other tablets, promoting good sleep patterns without the side effects. It is produced in a Welsh valley from natural plant materials chosen for their high antioxidant profile. Asphalia improves the state of natural sleep, fights off free radicals and improves general appearance.

Jan answers your questions

I wonder if you have any suggestions on glue ear? So far, the only help I have received is a hearing aid and soon I will be getting a second set of grommets.

Glue ear is the result of chronic ear infections and leads to hearing loss through fluid accumulation in the middle ear. We often find that Plantago is of great help.

I am 54 years old and have early type 2 diabetes. I am trying my best to bring my blood glucose levels and cholesterol levels down by reducing the amount of sugar in my diet, but am finding it very difficult. My doctor says I don't need any medication yet. I would like some help. Could recommend something?

Recent studies have suggested that simply improving glucose control will reduce the risk of cardiovascular disease in diabetics. Type 2 diabetes is very common in people over the age of 45 and most people who get it have an increased thirst and an increased need to urinate. They also tend to feel tired and irritable.

A diet regularly containing Fenugreek seeds has been noted to improve blood glucose control, which in turn improves blood cholesterol levels. Using Fenugreek seeds in the diet, or the specific amino acid known as Promilin as a food supplement, will be of help.