Most insomniacs know why they can’t sleep. They think too much. Their minds go too fast and never stop. When they go to bed, the unfinished thoughts of the day crowd in on them. Even if they fall asleep through sheer exhaustion, they often wake a few hours later and resume thinking where they left off. Anxiety, insomnia, stress and an overactive mind come as a package.

When we lie down and are no longer physically active, our thoughts naturally default to what we’ve just done or what we’re about to do. ‘At last,’ says the brain. ‘A chance to think without interruption.’ Unfortunately, the luxury of thinking is incompatible with sleep. Thinking is a kind of virtual miniaturised action that stimulates our musculature in the same way that real action does.

Many people first realise that stress is affecting their health when they have trouble sleeping. Sleep-onset insomnia is when people have difficulty falling asleep. Sleep maintenance insomnia is when people fall asleep readily but wake up later. Other people have shallow, restless, unsatisfying sleep and most of us get less sleep than we need. Unfortunately, only a few specific sleep problems benefit from medical interventions.

We all know the value of diet and exercise for good health but we almost completely ignore our need for sleep. Animals can survive for weeks without food but deprive them of sleep and they die within days. Conversely, good sleepers tend to live longer, happier and healthier lives than bad sleepers.

Poor sleep impairs many biological functions that are most active at night. These include digestion, immunity, growth and repair. The brain also needs good sleep for learning and memory consolidation. However the most obvious effect of poor sleep is that we feel sleepy. We feel underpowered and unable to cope during the day, which is a source of stress in itself.

Meditation works as a sedative by disarming the mental activity that keep us awake. It shifts our attention from thinking about the past and future into the immediate sensations of the body, and thus accelerates the biological process that takes us towards sleep. People frequently meditate to fall asleep and some learn it for this purpose alone. If you are tired and you meditate lying down you are very likely to fall asleep. The meditation would be over but that wouldn’t matter. A rapid descent into sleep is a good outcome. We can all do with more sleep than we usually get.

DAYTIME SLEEPINESS. Most of us now try to cope with a lot less sleep than our bodies and minds need. Feeling tired much of the time is now as normal as being overweight, and with similar detrimental effects on our health. Under ideal conditions we usually sleep and doze around 9-10 hours in total over a 24-hour period. Nowadays we sleep about an hour and half less than people did a century ago, and each year our average sleep time and quality continues to decline.

Poor sleep is often deadly. When we’re exhausted, we easily can fall into a ‘micro-nap’ without realising it. In these situations, no amount of coffee or will-power can stop the onset of sleep. We can fall asleep with our eyes open while doing routine tasks in bright, noisy surroundings.

This often happens while driving. We can easily travel a kilometre on the freeway during a micro-nap. According to some estimates, falling asleep at the wheel kills hundreds of thousands a year worldwide. It contributes as much to road fatalities as alcohol does.

Tired people suffer the same cognitive impairment as people who are drunk. Staying awake for 24 hours has the same effect on test subjects as three shots of whisky. Like drunks, tired people lack self-awareness and tend to overestimate their abilities. They confuse keeping going with doing things properly.

Because their brains are operating on the lowest possible setting, they can’t see alternative courses of action or foresee outcomes. They often fail to respond to or even notice anything unusual. Both the Exxon Valdez oil spill disaster and the Chernobyl nuclear meltdown were attributed to having sleepy men in control. They didn’t register what they were seeing.

WHY WE SLEEP. Many biological functions are designed to work best when we are asleep. The Relaxation Response is the opposite of the Stress Response. In recognition of its many functions, it is also called The Rest, Digest and Repair Response. It works best when cortisol levels are low and when the body is still.

During the day, the demands of thought and action get priority and other functions are put on hold. When we sleep and apparently do nothing, the priority shifts from action to the restoration of homeostatic balance. The processes of digestion, immunity, growth and repair come to life and can work uninterrupted by physical movement and sensory input. Their circadian peak of maximum efficiency occurs around midnight to 3 am, exactly opposite the cortisol peak at midday.

Growth Hormone is produced in truly massive amounts compared to other hormones and its production peaks in the deepest levels of sleep. Growth Hormone is essential for repair work in every cell of the body and for the generation of new cells. The digestive and immune systems require a huge turnover of new cells daily, and these suffer if Growth Hormone production is disturbed.

Bad sleep upsets our ability to fight infections. Immune function operates on a daily rhythm in step with the sleep/wake cycle. A single night of bad sleep can cause our levels of killer T-cells to drop by a quarter. These are the lymphocytes responsible for killing off infected cells including some cancers. In contrast, animal species that sleep the most tend have the strongest immune systems and the fewest parasites.

In sleep, the body removes the waste products of metabolism and the corpses of dead cells. It also brings in supplies, re-stocking the nutritional substances in the cells in preparation for the following day. For example, muscles have to rest to fully refuel their depleted supplies of glycogen (‘muscle-sugar.’)

Poor sleep disturbs the processes of digestion, metabolism and the excretion of waste products. Digestion is the extraction of nutrients from food. Metabolism is their use within the cells of the body. These processes take many hours from start to finish, and they work best if they are uninterrupted by physical or mental activity. This is why it feels natural to rest after a meal. It gets the process underway.

An insomniac is likely to have high cortisol levels even when asleep. Cortisol prevents the uptake of metabolic resources by the cells. It increases insulin resistance and causes blood sugar imbalances. In fact severe tiredness mimics the first stages of diabetes.

Sleep deprivation can also make us fat. Short sleepers and poor sleepers are more prone to obesity. As the production of growth hormone declines with stress and age, we convert energy to fat instead of muscle. Poor sleep accelerates that effect. It also increases the production of grhelin, a gastric hormone responsible for hunger and our tendency to overeat. You may notice how you often feel hungry when you wake up: that is the effect of grhelin.

THE BRAIN ALSO NEEDS TO SLEEP. The brain needs good sleep for learning and memory. At night, free from the onslaught of stimuli and the demands of action, the mind is able to review the events of the day. Since we use the same brain areas to both perceive the world and to process what has happened, we can’t do both at once. In dream sleep, we review and evaluate the day’s events in real time along with their full emotional content. In deep sleep, on the other hand, we strip the same events down to their essentials and code them into long-term memory.

This process prunes out the trivial details, emphasises what is important, drafts coherent, thumbnail stories and integrates it all into the databases of associated memories in the brain. If we don’t get sufficient downtime for this work, our minds become overloaded with unnecessary detail and too disorganised to work well.

The brain organ that consolidates new memories is the hippocampus. Most brain cells can’t regenerate themselves but the hippocampus is the exception. It can generate new cells in response to new memory tasks but this makes it particularly vulnerable to poor sleep. Elevated cortisol damages the genesis of new cells in the hippocampus just as it does in the digestive and immune systems. It also inhibits the growth of connections between the cortical cells that embed memory.

With sustained stress, the hippocampus can shrink in mass. This explains why poor sleep, stress and depression typically cause memory failures, poor concentration and a tendency to behave mindlessly. Cortisol also makes brain cells less sensitive to serotonin, the feel-good hormone whose activity is enhanced by Prozac and other antidepressants. Even a single night’s bad sleep is almost guaranteed to make us miserable the next day.

BETTER SLEEP TAKES COMMITMENT. Anxiety trains the body to have higher levels of cortisol regardless of the time of day. This means that although our cortisol will be at its lowest levels at 3 am, it will still be higher than it should. Once our sleep becomes ragged it is not easy to restore it. Insomnia, stress, ill-health and fatigue form a vicious feedback cycle that can be quite difficult to break.

So why don’t we take sleep more seriously? In medical terms, poor sleep is like the elephant in the room. It contributes to most common ailments but we ignore it. Sleep can be improved – there is no mystery about how – but it does take more effort than we are inclined to give it. It would involve changing some habits and taking time from other activities we would prefer to do, such as watching TV. It is not surprising that we find it all too hard to contemplate.

It doesn’t hurt to have a bad night or two. We can catch up on the sleep we’ve missed the next night or lie in bed longer than usual on the weekend. With chronic sleep deprivation however we gradually lose that ability to pay off the sleep debt.

As time-consuming as it seems to be, good sleep is worth the price. Better sleep can help if you suffer from indigestion or pain; if you feel perpetually tired or off-colour or are prone to infections; if you are more anxious, depressed or fat than you would like to be; if you feel unable to think clearly or see things in perspective; if you are so irritable or mentally absent that your relationships suffer; if your memory is shot, and if you feel older than you should.

Better sleep can help all of the above. It is quite possible that many of our common ailments would decline in severity and some would vanish if we just got enough sleep. We feel tired and run-down and unable to cope not because of some mysterious ailment. We are tired because we are tired. We are not getting enough sleep. If we slept more and improved the quality, we would feel a lot better.

HOW MEDITATION HELPS. Meditation helps insomniacs in several ways. It calms them down before going to bed. It defuses the thinking that tends to keep them awake. It initiates the sleep response as soon as they lie down. It helps them go back to sleep if they wake in the small hours. And if they do remain awake for whatever reason, it enables them to be calm and relaxed in that state instead of fretting.

Many insomniacs come to my meditation courses. Within a few weeks, about half are sleeping better and some are vastly improved. Often the results are immediate. People often tell me they sleep their best on the night after the meditation class.

Meditation is an excellent sedative and that is how most people use it. For those meditators who also become more self-aware, it gives extra benefits. If we become more mindful of our bodies and our emotional responses, we will eventually realise how certain activities help or hinder our sleep.

We usually can’t expect to fall asleep quickly after TV, computer activity, emotional excitement or any mentally demanding work. A big evening meal or coffee in the preceding hours doesn’t help. Lying in bed talking to a partner will make sleep difficult thereafter. Also recognise that if your partner snores or is restless in bed you are virtually guaranteed bad sleep yourself. You should seriously consider sleeping apart. There may be no other solution.

If we are stressed, we are unlikely to sleep well unless we can also relax occasionally during the day. Most of us have automatic strategies to help us do this. We have tea-breaks; we sit and read the paper mindlessly; we zone out at meetings or we potter round the house. These are times when we slow down and collect our energy. We take a few steps in the direction of sleep without going the whole way.

I train people to do short ‘spot-meditations’ for a similar effect. If you can deliberately relax a little many times a day, you are likely to sleep much better at night. You can release the daily tensions as you go rather than hoping to defuse them all when you hit the pillow.

It is extremely useful before you go to bed to briefly think over and sum up your day. Otherwise you are bound to do it the first few minutes in bed. It is much better to intend to go to sleep or to meditate the moment your head hits the pillow. Similarly, if you wake in the night or when you come back from the toilet. Trying to blank out or daydream or waffle your way back into sleep is unlikely to work.

Paradoxically, the best way to fall asleep or to go back to sleep is to make your mind as sharp and focused as it can be. In other words, to meditate well with no indulgent wandering. This is the only way to reliably cut free from the thoughts that keep you awake. Any meditation practice will do, but I often use music. If I switch on my bedside CD player and listen as intently as I can, I am usually asleep within a minute.

Meditation is useful even if you don’t fall asleep. Many people are so scared of not sleeping that the fear keeps them awake. If you lie there worrying, you will burn a lot of energy and get up in the morning exhausted. If you meditate however, your body can still rest, your mind can be calm and you are more likely to dip in and out of sleep. You can at least have a long restful meditation while awake in bed. While not perfect, this is much better than rising in the morning irritated and anxious.