The amount of sleep we require varies from person-to-person. Newborn babies sleep for around 17 hours a day, decreasing to around 13 to 14 hours after the first year of life. Adults need between seven and eight hours of sleep a night. However, this can vary greatly depending on the person.

For example, pregnant women often sleep more during their first trimester and anyone who is fighting off an infection, such as a cold or flu, will probably sleep more. In general, older adults sleep more lightly and for shorter periods. This may be a normal part of the ageing process, or it could be linked to a pre-existing medical condition or any treatment they are undergoing.

Teenagers need around nine hours of sleep. However, their frequent use of modern technology may trigger insomnia. Sleep patterns are linked to both light and hormones. In the evening when natural light dims, the body produces melatonin to signal that it is time for sleep. However, artificial light produced by TVs, laptops and mobile phones can interfere with this process.

In 2007, The Sleep Council published research that revealed that 30 per cent of youngsters only get between four and seven hours of sleep a night, while almost a quarter admit that once a week they fall asleep while watching TV, listening to music or with other gadgets running. Too little sleep creates a 'sleep debt' and, much like an overdrawn bank account, sooner or later, the debt needs to be repaid. While one night of disturbed sleep will have relatively little impact, issues arise when a person frequently suffers restless nights or regularly burns the candle at both ends.

Insomnia can be a very debiliating condition