Loughborough University
Leicestershire, UK
LE11 3TU
+44 (0)1509 263171

School of Sport, Exercise and Health Sciences

Loughborough Sleep Research Centre

Our Research

Falling asleep at the wheel
Sleep loss and 'executive thinking'
How much sleep do we need?
Mobile phone electromagnetic radiation and sleep

Falling asleep at the wheel

Why do drivers fall asleep at the wheel? - Falling asleep is always preceded by a period of increasing sleepiness, which drivers are quite aware of, to the extent that will do things to keep themselves awake (opening window, turning up the radio, stretching etc), but continue to drive rather than 'take a break'. Why do they fail to heed these warnings, believing they won't actually fall asleep and are 'safe' to drive? Young men are the most likely persons to do this, even when they are struggling to stay awake.

Driving and Obstructive Sleep Apnoea - Very heavy snoring alternating with 'gagging' sounds, and a heaving chest are the usual signs of this disorder, which causes much disruption of sleep and, as a result, excessive daytime sleepiness. Sufferers can remain like this for many years until treated. The disorder is usually treatable, but requires referral to a sleep disorders clinic. Using our 'state of the art driving simulator', we are looking at the ability to 'drive alert' in those people who have been successfully treated.

Low Blood Alcohol Levels, Well Under the Legal Driving Limit, Worsen Sleepiness - Just one lunchtime drink, giving a blood alcohol level that would easily pass the breathalyser test could still be dangerous for drivers, because of alcohol's impact on the natural afternoon dip in mental alertness. This combined effect of sleepiness and moderate alcohol intake is even worse for drivers who have not slept well the night before. We are looking at driving in the small hours of the morning (when one would normally be asleep), after having had only a few drinks that evening but are well under the legal limit.

Countermeasures - Sleepy drivers should stop driving and take a 30 minute break at a safe place. We have shown (now recommended in the Highway Code) that a caffeinated drink immediately followed by a short nap before the caffeine kicks in, make an ideal combination for combating moderate sleepiness. Despite advertising claims, some caffeine products are much better and others in this respect, and drinks with a very high sugar content can worsen sleepiness. We are assessing these products and claims.

Sleep loss and 'executive thinking'

Apart from causing 'sleepiness', sleep loss particularly affects the more subtle forms of human behaviour known as higher 'executive' function, largely controlled by the prefrontal cortex - a brain region at its most advanced in humans. It is the hardest working part of the cortex during wakefulness - which may be why it seems so vulnerable to sleep loss. Here, sleep loss effects include: rigid thinking, reduced verbal fluency, perseveration, impaired working memory, inability to deal with novelty and the unexpected, and less inhibited social behaviour. Interestingly, unlike 'sleepiness' these deficits show much less of a 24 hour circadian rhythm, but steadily worsen with sleep deprivation. Contemporary '24/7' society requires many people to work with sleep loss, whether this be through shift-work, long working hours or simply from late night socialising. Despite the large number of sleep loss studies that have been undertaken, these aspects of sleepiness are not so well understood, which is the reason why we have been investigating this topic over the last 10 years or so.

'Distractibility' under Monotonous Work Settings. Another aspect frontal lobe function is the ability to maintain attention to a task when there is competing distraction. Sleepy people seek stimulation to remain awake, and will look around for something new to look at, becoming more easily distracted from a task, especially if it is dull and boring. Most laboratory studies measure sleepiness using these tedious but sensitive tests, within a sterile room, purposely devoid of any distractions. However, by creating such an environment, few, if any studies of sleep loss have assessed the impact of distractions in any systematic way. We find that sleepiness increases vulnerability to distraction and that the propensity to distraction is, itself, an important measure of sleepiness.

The Social Neuroscience of Sleep Loss. A new area of research into this executive function is 'social cognition' - the ability to comprehend non-verbal, social signals from others and make appropriate judgments. The effects of sleep loss on these abilities is a new research programme, well under way.

How much sleep do we need?

Findings in the UK over the last 40 years consistently show the average daily sleep for adults is about 7¼ hours, which is no less than it was a hundred or so years ago. Mortality seems to be lowest in those sleeping around 7 hours a night. Nevertheless, there are claims that we should be sleeping for longer (8-9 hours), and that habitually short sleep ('sleep debt') also leads to physical problems such as obesity, the metabolic syndrome ('glucose intolerance'), and maybe even diabetes. We contest these claims, that 'sleep debt' is worse today than it ever was, or that it really is a risk factor for obesity, etc. Often, small statistically significant findings are wrongly assumed to be of medical importance, when they are not. This is an area fraught with these difficulties. We have an ongoing research programme looking at all this.

Have a nap - Sleep, like food and drink, can be taken to excess of biological needs. We can sleep for longer in the mornings - but do we always need this extra sleep? - as, typically, all it seems to do is to reduce the natural 'afternoon dip'. But how does this compares with a short afternoon nap or even caffeine? We are finding in ostensibly alert people who are not sleep deprived but, nevertheless, can extend their morning sleep by around 90 minutes, that a 20 minute, timely afternoon nap, or even an afternoon cup of caffeine are as good as the morning sleep extension in removing the dip and improving evening sleepiness.

Mobile phone electromagnetic radiation and sleep

Research from other laboratories has shown that the radio waves from a mobile phone affect the electrical activity of the sleeping brain (the 'EEG')'. However, these studies have mostly used one standard radio frequency, whereas the phone signal differs depending on whether we are talking, listening or leave the phone in 'stand-by' mode. We have separated out these three signals and find different effects on the EEG. This research program, in conjunction with the Centre for Mobile Communications Research, here at Loughborough, has shown that 30 minutes exposure to the 'talk' mode signal delays sleep onset.