Insomnia is the inability to fall asleep, or to stay asleep long enough to get a proper night's sleep. The occasional night with too little sleep can make you feel very tired the following day. This can be dangerous if you're driving or operating machinery. Insomnia which goes on for a long period of time can cause health problems such as high blood pressure and diabetes, or make you more likely to become overweight.
There are two types of insomnia, called primary and secondary insomnia. Primary insomnia has no obvious cause. Secondary insomnia is caused by an underlying problem, such as a medical condition or psychological problem such as grief and depression.
Insomnia can be described as either short-term or long-term. Short-term insomnia lasts for between one and four weeks. Long-term (chronic) insomnia lasts for more than four weeks.
More women experience insomnia than men. As you get older, you're more likely to have difficulty sleeping. One in every two people over the age of 65 has insomnia at some time.
The reasons why we need to sleep aren't fully understood. However, the effects of a lack of sleep suggest that you need sleep in order to rest and repair your body. Sleep happens daily and is a period when you're unconscious and unaware of your surroundings. Your sleep is made up of five different stages which are listed below.
- Pre-sleep - when your muscles are relaxed and your heart rate and breathing slow down.
- Light sleep - when you're lightly asleep, can still be woken up easily and won't feel confused.
- Slow wave sleep - the time when you might sleepwalk or talk in your sleep.
- Deep slow wave sleep - when you're hard to wake up and, if someone does wake you, you may feel disorientated and confused.
- Rapid eye movement (REM) sleep - when your eyes move from side to side and your brain is very active but your muscles are totally relaxed. You dream mostly during REM sleep.
The stages of sleep occur in cycles, moving from REM sleep to deep sleep and back again during the course of a night. You may have five cycles of sleep during a typical night.
The amount of sleep you need is very individual. Some adults need eight hours sleep whereas others can manage with much less. People of different ages need different amounts of sleep. A baby needs about 17 hours a day, whereas an older child needs about nine to 10 hours a day. Most adults need seven to eight hours sleep.