The myths about why insomnia is harmful

The amount of sleep a person requires is genetically determined. Families tend to sleep for the same amount of time. The average sleep requirement is 8.1 hours every 24 hours although the range is from 6 hours to more than 10 hours. Put another way 50% of us need more than 8 hours! It is not possible to alter this requirement.

Insomnia is not simply short sleep which might be normal for the individual but rather that there is an impact of this short sleep on daytime functioning, which is one of the harmful effects. Those who need less than the usual amount of sleep because of the genes would function quite normally in the day.

Thus insomnia is a subjective complaint of difficulty getting to sleep, staying asleep or sleep that is unrefreshing but importantly with daytime consequences. Reasons for this lack of sleep are many including alterations of the body clock which delay sleep onset. This is called Delayed Sleep Phase Syndrome. The genetic underpinnings of this are well understood with one of the 10 clock genes having alterations which lead to a delay in the drive to sleep.

There can also be conditions which disturb the continuity of sleep. The common ones are those related to snoring and interrupted breathing, and repetitive limb jerking. It perhaps goes without saying that psychiatric disturbances have a big impact on sleep with depression and anxiety being the main issues.

However, the most common form of insomnia is a learned behaviour. This is a factor behind the development of some difficulty sleeping in one third of the population at some point in the year. This one third of the population has a measurably different physiology in terms, for example, of increased levels of cortisol and adrenaline which allow that person, that physiology, to be more arousable. Another consequence of this hyper-aroused state is that in spite of the lack of sleep there is a tendency not to be sleepy in the day. Importantly, for one third of that one third of the population that is one in 10, the problem persists, because it can.

Although insomnia for a long time has been thought of as an irritation rather than having health implications, the current understanding, is that short term consequences include fatigue, concentration problems and memory impairment (sleep is important for memory consolidation), and the longer-term consequences affect both physical and mental health. Insomnia is associated with depression and of course anxiety and stress, which often raises the question as to 'the chicken and the egg'. Is anxiety and stress leading to insomnia or does insomnia lead to stress and anxiety?

It has also been shown that insomnia can lead to reduced productivity, to more absenteeism from work and to alterations in the quality of life, even to the extent that measures of quality of life may be as affected as in conditions like heart failure and Parkinson's disease. There is also evidence that insomnia has an impact on immune function. For example, when individuals are exposed to colds those that become symptomatic are more likely to have prior limited sleep.

Until recently the association of chronic insomnia with significant medical morbidity was not fully established especially given that the diagnosis of insomnia has for a long time been based on subjective complaints. However, when insomnia is documented to be associated with short sleep it is associated with neurocognitive impairment. Along with this is also evidence for a development elevation of blood pressure in the long term.

It is always worth remembering that some other medical problems can precipitate insomnia. These include snoring and the related sleep apnoea. Snoring is extremely common of course, with a basis in the anatomy of the throat airway and may develop in a half of men in middle age. Importantly this is commonly associated with some interruptions to breathing, so called sleep apnoea, which may affect a half of snorers, that is about 1 in 4 middle aged men. These interruptions to breathing develop first in dreaming sleep when the body is physically paralysed so as to prevent us acting out our dreams, this paralysis effecting the throat muscles as well, so that the tendency for the throat muscles to collapse is much more likely in dreaming sleep, and linked to this in some is a potential for being woken and therefore perceiving this as insomnia. There may also be limb movements during sleep. These are most commonly associated with the waking complaint of discomfort in the legs, so called Restless Legs Syndrome. Other general medical problems may also be relevant such as asthma or acid reflux.

Sleep is so important for our health that attention should be paid to factors that might influence sleep. This is the notion of sleep hygiene. There are some physical things that impact on sleep. Sleep is associated with a fall in body temperature (a full degree centigrade), the hotter the body is during the day the more likely it is to go to sleep and to stay asleep. Although a warm bath an hour before bedtime is helpful, the best way to raise body temperature is to exercise for a sufficient length of time, for example 20mins of something like running or cycling. It is important to realise that it is not being fit that makes us sleep well, it is the elevation of body temperature which needs to be there at bedtime. Therefore, exercise in the morning will not help sleep whilst exercise in the evening will contribute to disturbed sleep because of an increase in adrenaline. Exercise is found to be best between 4-7pm. This may not be ideal for the working individual but nevertheless this is the time it is most productive.

Another physical issue is caffeine. In a physiology that allows this insomnia to develop, that is the hyper-aroused physiology, caffeine becomes a potent stimulant. Although many of can take caffeinated drinks and not be affected, the insomniac might well be. In this context it is relevant to appreciate that caffeine has quite a long half-life, more than 5 hours. This means that if one takes a strong caffeinated drink such as coffee, tea, coca cola in the morning there may still be caffeine in the system in the evening.

Some food in the stomach is thought to be a good thing for sleep as long as it is not too much or too spicy. A bedroom conducive to sleep of course is best cool, dark and quiet (bats are phenomenal sleepers in their cold dark caves!) earplugs and eyeshades are useful in this respect and getting up at a regular time. Prior to sleep, if getting off to sleep is difficult, then one needs to be aware of the effect of light on our body clocks. Light is the drive to timing of the body clock and exposure to light from electronic devices such as computers and cell phones before bedtime has a potential for delaying the body clock. It is known, and has been for some 10 years, that the wavelength of light that specifically does this is the blue light wavelength and applications have been developed withdraw this waveband from computers and cell phone which may be helpful.

The sleep hygiene rules, as I have said, should be attended to by everyone by in the setting of an insomnia other behavioural techniques are of course helpful. This would include dismissing intrusive thoughts which may prevent the onset of sleep or the return of sleep with mindfulness meditation is in a sense giving one permission to be awake in the night without entertaining thoughts or feelings which are not actually happening. There is literature on the value of mindfulness as a prophylactic in managing someone's insomnia.

Melatonin is a naturally occurring hormone that is secreted at night, it is called 'the dark hormone' for that reason. Its function is, in part, to time the many body clocks that exist in the different organs. It is of course available as a medication or as a supplement and is used as an aid to sleep. Melatonin is not a powerful hypnotic, or a sleep inducer, like traditional sleeping tablets but does induce a slightly soporific feel if taken in the evening. It is important to realise that any light exposure during the night, for example if someone is awake and is using electronic devices, then the Melatonin we manufacture ourselves is 'switched off. For this reason, supplements may be beneficial. It is also used to help time the body clock. Melatonin has a direct effect on the clock with the potential of advancing the timing of the clock when taken at an appropriate time. Generally, 3 hours before preferred sleep onset.