Sleep: The secret to sleeping well and waking refreshed

• painkillers (e.g. Anadin)

• herbal preparations (e.g. Guarin)

• some cola drinks

• Lucozade

• ‘energy’ drinks (e.g. Red Bull)

To find out how much caffeine you are really consuming, see the main caffeine offenders, opposite.

The absorption and metabolism of caffeine

Varied or little effect

Heredity Caffeine metabolism is controlled by many genes and racial differences exist

Gender Exercise and stress have no reliable effect on the absorption or metabolism of caffeine

Pregnancy There are no placental barriers to caffeine so the foetus is continuously exposed

Slowers-down

Oral contraceptives, late pregnancy and liver disease cause caffeine to be eliminated more slowly

It has been thought that grapefruit juice, though not other citrus juices, slows down metabolism. The data for this has now proved controversial

Some drugs like cimetidine, disulfiram, even alcohol, may slow down caffeine metabolism

Speeders-up

Smoking induces liver enzymes which break caffeine down

Rifamprin

The main caffeine offenders

did you know?

Coffee is an ancient commodity. In AD 575, about 500 years before it became a hot beverage, the crushed beans were mixed with fat and used by Ethiopian mountain warriors to provide an energy boost during long treks and warfare.

must know

Sugar

Sugar does not give you energy. A study carried out at Loughborough University, UK evaluated the energy-giving effects of sugar on ten healthy young adults. Their sleep was restricted to five hours the night before so that they would be sleepy in the afternoon, and half were given a ‘high-energy’ drink containing high levels of sugar but low levels of caffeine, and the other half a drink containing low levels of both. When submitted to vigilence and sleepiness tests the high-sugar drinkers made twice as many errors and showed higher levels of sleepiness than the control group, as well as delayed reaction times.

Sugar

Sugar can have a negative impact on sleep patterns because of its effect on insulin and blood sugar levels. It is released into the bloodstream to give you that instant ‘high’, but then departs from your system just as quickly, leaving you exhausted. In fact, you feel so tired that your instant impulse is to have yet another sugar fix to make you feel better. And so the cycle goes on. The continuing effect of these highs and lows can leave you feeling drained, or – depending on when you last had your sugar dose – over-excited, with pounding palpitations that stop you from sleeping. The disruptive impact on blood sugar levels can also cause sleep-disrupting hormonal imbalances in women. Sugar is found not only in biscuits and sweets, but also in fizzy drinks, refined wheat, tomato ketchup, baked beans and many processed foods. Read all food labels carefully.

‘Good sleep’ foods

There is some evidence to suggest that eating slowrelease energy foods, or low glycaemic index foods, (foods that keep blood sugar levels stable), may improve general health and sleep quality (as well as helping the individual to lose fat). The idea is that the lower the glycaemic rating of a particular food, the more slowly energy, in the form of glucose, will be released into the body (see Low glycaemic index foods, opposite). Thus glucose and insulin levels are prevented from plummeting during the night, which may be beneficial for sleep. Foods such as turkey and dairy products may also be helpful, as they are high in tryptophan – the amino acid that the body uses to produce the sleep-inducing hormones serotonin and melatonin (see pages 16-17).

Low glycaemic index foods

What to eat when

When we eat can be as important as what we eat. This is a question of balance. Hunger can keep you awake, so having a light snack before you go to bed can be advisable. On the other hand, going to bed with a stomach that is over-full may cause indigestion and feelings of discomfort that will keep you awake all night, especially if you have eaten fatty and rich foods that make your digestive system work harder.

must know

Diet

Studies on the effect of milky or malted drinks on sleep appeared to show benefits. However, evidence does suggest that non-milky herbal teas are just as effective in promoting a good night’s sleep.

As a rule it is best to eat your main meal at lunch time or early evening, and to eat small amounts of light food at night-time. Snacking if you wake during the night is not a good idea. Your body may come to expect food at this time, and you will carry on waking up in the night to satisfy your hunger.

Lifestyle

The way we live can provide a crucial pointer to our sleep problems. Stress, shift work, smoking and jet lag can all be contributing factors. It can be hard to change the habits of a lifetime, but when it comes to sleep, small changes can go a long way.

must know

Sleep in ex-smokers

Sleep disturbances and related daytime symptoms may leave the ex-smoker less able to cope with everyday stress, therefore increasing the likelihood of relapse. Studies have found that ex-smokers complaining of broken sleep are the most vulnerable.

Stress

This is by far the most common cause of insomnia, and can be short-term (caused, say, by the arrival of a new baby) or prolonged (juggling a career and family, or caring for someone who is ill).

Stress has been with us since ancient times, when our forebears used the natural ‘fight or flight’ response to deal with threatening situations such as attack. The causes of stress may be different now but the basic response is still there. ‘Fight or flight’ increases breathing rate, heart beat, and the production of the stress hormones cortisol and adrenaline; mental awareness is heightened and blood rushes to the muscles; the body is on red alert to deal with whatever crisis it is faced with. Doctors acknowledge that we all need some degree of fight or flight in our lives because it satisfies a primitive urge for survival. But prolonged stress can have damaging effects on both health and sleep. It is well documented that long-term stress can lead to anxiety and depression – two major sleep disruptors that can be the cause of many sleep-related disorders (see Chapter 6). Acknowledging when things have got out of hand and taking stress-relieving measures is the only solution (see Chapter 5).

Smoking

Despite the well-known risks of smoking, this still remains a major problem – mostly due to the highly addictive nature of nicotine itself, which can make it extremely difficult for habitual smokers to stop. Withdrawal symptoms can begin quickly – often within a few hours of the last cigarette – leading to sleep disturbances. The brain’s nicotine receptors respond very rapidly to the lack of nicotine, which is why for habitual smokers the first cigarette of the day can bring the most relief, even though smoking in the night can cause disrupted sleep.

must know

NRT

Nicotine replacement therapy (NRT), which reduces the urge to smoke, is recognized as an effective aid to stop smoking, and increases cessation rates. Unfortunately, nicotine patches can sometimes be over-stimulating, leading to insomnia. The 24-hour patches are less problematic than the 16-hour ones, however.

The combined impact of the brain’s response to the lack of nicotine and the breathing problems that all smokers invariably suffer from mean that nicotine is most definitely not good for sleep.

Sadly, smoking is a vicious cycle that creates numerous problems. Many people start the habit because they find it useful for maintaining or increasing their alertness. (When inhaled, nicotine quickly stimulates the heart, brain and adrenal glands.) This is particularly true among young people and sufferers of sleep-related disorders. The need to boost alertness with nicotine reinforces the use of tobacco. Tobacco disturbs sleep, reducing daytime alertness, which in turn reinforces the use of tobacco. Apart from keeping you awake, there is evidence to suggest that nicotine may affect sleep in other, more indirect ways too. Smoking is believed to affect blood sugar levels, which can make you irritable, and smokers are also statistically more likely to be coffee-drinkers, the combined effect of nicotine and caffeine having a disastrous long-term impact on sleep duration and quality.