Alertness is a key aspect of consciousness. When we are not alert, we do not function at the peak of our mental ability. Maximizing alertness, therefore, helps us to function more efficiently. It can also help us to avoid potentially dangerous errors, for example, when driving, working with machines, or making vital decisions.
The difference between being ‘very sleepy and feeling wide awake is usually obvious, and we can recognize these extremes of alertness both in ourselves and in other people. Less obvious, however, are the different degrees of alertness that occur throughout a normal day. Many scientists distinguish between two kinds of alertness – tonic and phasic. Tonic alertness is associated with biological rhythms, especially the daily cycle of waking and sleeping. Typically, our alertness is lowest in the very early hours of the morning (3 to 6 am) and highest during the late afternoon and early evening (4 to 7 pm.). We also tend to be more alert during mid-morning (10 am to 1 pm) than in the early afternoon (1 to 3 pm).
Tonic alertness is controlled largely by a part of the brain called the reticular activating system (RAS), which arouses the rest of the brain when it is itself stimulated. Evidence for this comes from studies that have found that damage to the brain’s cem above the RAS can cause continuous sleep, whereas damage below the RAS does not impair normal cycles of alertness and sleep. Electrical stimulation of the RAS also causes sleeping animals to rake up. Recent research has demonstrated that other parts of the brain, including the thalamus and hypothalamus, are also involved in the sleep-wake cycle and alertness. The other kind of alertness, known as phasic alertness, is short-term, temporary arousal prompted by new and important events around us, particularly potentially threatening ones.
Typically, phasic alertness lasts for just a few seconds. For example, if you suddenly hear a loud noise, you will automatically turn to see where it is coming from. Many other bodily changes are also triggered – dilation of pupils, an increase in heart rate and breathing, tensing of muscles, and so on. These are all part of the response to the potential danger or crisis and prepare your body either to run away from the threat or to stand and fight it. Accordingly, this mechanism is often called the ‘fight or flight’ response.
The Impact on the Environment
Environmental factors are important in maintaining alertness – a fact often overlooked in the design of offices and factories. Many people work in offices where light, temperature, and noise levels are optimized for comfort rather than maximum alertness; indeed, many places of employment are more conducive to sleep than work. Sitting in an artificially controlled atmosphere while staring at a computer monitor and lulled by the hum of the fans, it is unsurprising that many of us sometimes find it difficult to concentrate.
It is useful to remember that cool, dry air – especially on the face – can help keep you alert, whereas heat and humidity tend to make you drowsy. Therefore, turning down the therm stat and opening windows are all simple, healthy ways to improve alertness. Another tactic to help maintain alertness, particularly during a difficult or boring task, is to take regular short breaks.
Food and alertness
Food and drink may have a direct bearing on alertness. People often feel sleepy soon after eating a large meal because of the diversion of blood and oxygen away from the brain to the digestive areas. In addition, certain foods, including bananas, milk, chicken, and turkey, promote sleepiness in certain individuals. Conversely, a simple glass of water can make you feel more awake. Many people use caffeine in the form of coffee, tea, and cola drinks to boost alertness temporarily. Reliance on caffeine can be counteder productive because the more you use it, the more you need to produce the same effect. On the other hand, some people are so sensitive to caffeine that just one cup of coffee can disrupt their sleep.
In recent years, there have been numerous claims that food supplements can reduce fatigue and increase alertness. Compounds and preparations such as acetyl- L- carnitine, DMAE, Ginkgo Biloba, ginseng, L-phenyl alanine, L- tyrosine (the last two being amino acids that are commonly found in high-protein foods) have all been touted as substances that enhance alertness. In most cases, these claims have not been substantiated by scientific evidence.
The role of sleep
The single factor that exerts the strongest effect on alertness is sleep. Experts agree that most adults need to sleep for seven to eight hours every night, while children and adolescents need longer. Less than five hours per night over several days can start to cause noticeable mental impairment, including loss of alertness during waking hours; less than three hours per night for a week or more can cause serious health problems. In laboratory experiments on animals, continued sleep deprivation has been found to cause death – chiefly through damage to the immune system. It is, therefore, essential to develop regular sleep habits that support rather than conflict with the biological clock in our brains.
The 24-hour society
ln, in today’s world, many people work shifts that do not fit in with natural patterns of activity. Some people can cope with changing their patterns of wakefulness more easily than others, but all shift workers must avoid major sleep loss so they can be alert when they need to be. The dangers of shift workers not being alert, especially in the early morning, may have contributed to major industrial accidents such as those at Three Mile Island and Bhopal and the Exxon Valdez running aground. It is also well documented that road traffic accidents are relatively more common in the small hours.
Part of the reason that alertness drops during the night is that darkness increases the concentration of sleep-inducing melatonin in the brain. So, one way of maintaining alertness when working shifts is to make sure that the working area is brightly lit. In the USA, some people take melatonin pills (not licensed for use in the UK because of concerns over their safety) to help them adjust to a new daily rhythm of work, alertness, and sleep.
A useful approach to maintaining alertness throughout the working day, whether you are a shift worker or not, is the judicious use of naps. Your potential for alertness is influenced not only by the amount of sleep you had the previous night but also by how long you have been awake. So, for someone who has to work in the morning and evening, an afternoon nap will decrease the number of continuous hours of wakefulness and may help to maintain alertness. Care needs to be taken, however, that the nap does not have an adverse effect. If it is too long, the person may find it hard to get to sleep later. Also, the period immediately after a nap can be characterized by a lack of alertness – often referred to as ‘sleep inertia. ‘ Generally, though, studies of strategic napping have demonstrated that it can help to maintain performance and alertness.
How to Measure Your Alertness
Levels of alertness are measured by psychologists using reaction times. A simple measure of how alert you are can be obtained with the help of a friend and a ruler at least 40cm ( 15 in) long.
- Ask your friend to hold the rule vertically between your thumb.
- And finger at the top of the rule. Position the thumb and finger of your preferred hand at the bottom of the rule about 2- 3cm (in) apart so neither is touching the rule.
- Your friend should then drop the rule without warning. As soon as you see the rule falling, grasp it between your thumb and finger. Use the position of your thumb against the rule’s markings to see how far it fell before you caught it.
- Repeat this several times and take an average of the readings. Then, try this test at different times of the day or before and after meals and drinks to gauge how much your reaction times vary.
Naps in Flight
Long-haul flight crews regularly experience extended periods of duty while crossing multiple time zones, which results in disruption of daily cycles and loss of sleep. In a recent study, a group of pilots was monitored to examine the effects of napping on board during off-duty periods of flying 747 aircraft, which have a flight crew of three. Some pilots were encouraged to nap while off-duty, while others were not allowed to sleep at all on the flight deck. Their performance was then compared over 12 days that involved eight flights. Measurements of alertness were made using both subjective techniques, such as log books and anecdotal reports, and objective measures, such as physiological recording of the brain and eye activity. Of those pilots who were allowed naps, nearly all (93 percent) went to sleep, with the average sleep session lasting about 26 minutes. The study found that the ‘no nap’ pilots showed reduced performance, especially on night flights, whereas the ‘nap’ pilots had significantly better performance and physiological alertness. Partly as a result of this real-life research, many airlines have now put in place programs for controlled rest periods for their flight crews.
Chocolate as a Stimulant
Chocolate has been used as a stimulant in many cultures. It was revered by the Aztecs and Maya, who used it in religious ceremonies and valued it more highly than gold. Chocolate is made from the seeds of the tropical cacao tree, Theobroma cacao, a name derived from two Greek words: ‘theos,’ meaning gods, and ‘broma, ‘meaning food. Its active ingredients include caffeine and theobromine, both of which are potentially addictive alkaloid stimulants. Despite its caffeine content, chocolate does not seem to keep people awake at night and is widely used as a bedtime drink. Theobromine has been proven to improve the performance of racehorses, and feeding racehorses chocolate, cocoa beans, or theobromine before a race is now illegal. It has not yet been shown that chocolate improves alertness or other performance criteria in humans – but that does not seem to reduce our appetite for this ‘food of the gods.
