Insomnia is defined as the difficulty getting to sleep, staying asleep or having non-refreshing sleep.
It means difficulties occur three or more times a week, persist for at least a month, and can impact on our ability to function properly during the day.
Persistent insomnia can affect personal lives and performance at work, delay recovery after illness and is a major cause of depression.
Symptoms can include:
- Lying awake for a long time before falling asleep.
- Waking up several times in the middle of the night.
- Waking up early and not being able to get back to sleep.
- Feeling tired and unrefreshed by sleep.
- Inability to concentrate during the day.
- Irritability due to lack of sleep.
Most people with insomnia report daytime fatigue but few feel sleepy, says Professor Kevin Morgan of the Loughborough University's Sleep Research Centre.
“Instead, they remain in a wakened state, feeling fatigued, lethargic and without vitality.”
How much sleep?
Most adults need between six and nine hours sleep each night. Some people can feel perfectly rested with a shorter period. Former Prime Minister Margaret Thatcher is well known for only needing four hours’ sleep a night.
Newborn babies can sleep for 16 hours a day, while children of school age need an average of 10 hours. Most people over 70 tend to be light sleepers and need less than six hours sleep per night.
So how much sleep do we need? “Simply put, enough to make you refreshed and able to function efficiently throughout the next day,” says Professor Morgan. How many hours that is depends completely on the individual.
Insomnia tends to be more common among older people and women. The level among young people is around 4% whereas it affects up to a third of people aged over 65.
Gender differences can probably be explained by differences in lifestyle, hormonal profiles, and may also reflect lower levels of reporting among men.
“Experiences like periods, the menopause, pregnancy and child rearing are all factors which can contribute to insomnia,” says Professor Morgan.
Contributing factors
Research suggests that many patients with insomnia present the same three characteristics:
- Predisposing factors: they experience higher levels of anxiety, intrusive thoughts and are easily distracted.
- Precipitating factors: traumatic experiences can trigger insomnia, such as the death of a loved one.
- Perpetuating factors: insomnia evolves into a long-term condition because of poor sleep habits.
Professor Morgan says: “Approaching insomnia in this way helps to explain why some events such as illness, sports injuries, stress, childbirth and bereavement can disturb sleep in most of us, but produce chronic insomnia in only the predisposed minority.”
