We've all suffered from the occasional sleepless night. Stress and anxiety are common causes, but depression, the use of prescription drugs, overeating in the evening, or changes in work schedule can lead to insomnia.

There are many self-help remedies geared towards getting a good night's rest - common sense approaches such as a warm bath and limiting caffeine. However, if your insomnia lasts for several weeks, it can affect judgement, coordination and memory - and even suppress the immune system. If this is the case, it's time to see your doctor.