Most adults need about 8 hours sleep a night. It is the body's natural "maintenance" period, when we repair ourselves and prepare for the coming of another new day.

Unfortunately, many of us only achieve 6 hours or less per night and so create a cumulative sleep deficit. We know lack of sleep affects our concentration, our alertness, creates mood swings, and can affect our short term memory.

There is evidence that sleep apnoea can have an effect on the left hippocampus and so memory will be compromised and spatial awareness may even be altered. In children sleep apnoea is thought to even cause brain damage - research has shown altered ratios of neurochemicals that indicate injury to brain cells.

If your partner or a family member snores and stops breathing it is essential they go to a sleep clinic and get the problem sorted. Apnoea is becoming more and more common because of the increase in obesity and once set in it can become a vicious circle of not having enough energy to exercise to lose the weight.

During the first part of our sleep cycle our bodies are repairing the damage caused during the day by our day to day activities. During this time we may dream and the dreams are fairly light and insignificant. Then we will go into the REM (Rapid Eye Movement) state, with increasing REM towards morning. During this time our bodies become paralyzed, presumably so we don't act out our dreams, and the brain waves during REM are very similar to our waking state, which is probably why our lucid dreams are so much like being conscious. The difference between the two dream states however is quite marked. During REM, our dreams are often confrontational, negative, dealing with problems and quite often "weird". The reason for the weirdness is that we dream in metaphors, so somewhere in the dream will be elements of our experiences. There are some schools of thought who maintain that dreams are our subconscious bringing issues to our conscious mind, Jung for example seemed to think that it was all symbolic - understand the symbol and you can interpret the dream. Over the years a whole industry in dream interpretation has sprung up. However, scientific research into sleep has largely dismissed this.

Others believe that we dream negatively because it's a way of working through our problems. Animals, it has been found, when the ability to be paralyzed during REM has been removed, will hunt in their sleep. Some experts have put forward the idea that REM could be programming our minds for how to do something in the future.

More information about sleep research

Top 10 tips for better sleep

1) Don't drink caffeine after about 6pm. If you like coffee after a meal, make sure it's decaf. Don't drink alcohol either, because although it acts like an anaesthetic, it will make sleep later on in the night problematic.
Alcohol suppresses deeper stages of sleep, shortens and fragments sleep. In addition, alcohol tends to relax the upper airway muscles, so that if a person has a sleep-related breathing disorder, such as obstructive sleep apnoea, alcohol can worsen this condition and cause more disruption in the person's sleep.

2) Make sure the bed is clean, comfortable, the bedroom cool.

3) Try not to be in bright lights at least 3 hours before going to bed, or to listen to loud stimulating music. I'm afraid clubbing and sleep do not mix, boring as that sounds.

4) Don't watch TV in bed. Not only is it stimulating the brain - we quite often get caught up emotionally in films and TV programmes - but latest research has also found that blue light from modern TV's is especially good at suppressing melatonin, one of the brain's "feel-good chemicals", so watching TV at night may reduce the nocturnal rise in melatonin, and we may find ourselves feeling depressed.

5) Have a warm bath 30 minutes before going to bed. This helps the body temp to rise slightly then cool; this cooling effect fools the brain into thinking it's going to sleep and so helps the person go off to sleep faster.

6) If you have lots of thoughts going round in your head, try listening to a relaxation CD, or some classical music that's relaxing.

7) If you are not asleep within 30 minutes, get out of bed and go and sit somewhere until you do feel tired. Do not lay there waiting for hours and then sleep later the next morning. This can cause erratic sleep patterns that can take time to reschedule. Always go to bed at the same time and get up at the same time.

8) When you get up in the morning, try and sit or stand in a brightly lit place for 30 minutes. That means having breakfast outside in the summer or bright overhead lights in the kitchen in winter.

9) Get good exercise during the day, but not too late into the evening. This will help you feel tired. It is shown that exercise improves your mood, so for people experiencing disturbed sleep during depressed periods (usually waking up early in the morning feeling exhausted) then exercise can help improve this.

10) Sleep is important. If you have children who are demanding your attention constantly throughout the night, then you may feel you never get enough sleep. Try and sort that out as a problem first. Try and encourage other family members to help. If you have partners that tosses and turns, think about getting 2 single beds, or if they snore, sleep in separate rooms.