The links between sleep and health

Lack of sleep can be brought on by a number of factors, including sleep disorders, shift work and a busy lifestyle. Previous research has shown that sleep plays an important role in laying down our memories and ensuring that our metabolism, immune system and regenerative processes work properly. Furthermore, poor sleep is a known risk factor for weight gain, hypertension and type 2 diabetes.

The aim of the SLEEP RESTRICTION team is to identify the molecular, physiological, behavioural and sociological factors behind sleep loss and clarify its physiological and behavioural consequences. The project’s members are particularly interested in how age, gender, genetics and social background influence sleeping patterns and how sleep loss influences people’s risk of developing obesity, cardiovascular diseases and diabetes.

The effects of partial sleep deprivation

One of the project’s most important findings to date concerns the effect on health of partial sleep deprivation. In the study, young, healthy adults were restricted to just four hours’ sleep a night for five nights. Over the course of the study, their ability to perform complex tasks declined, and the scientists detected problems in the subjects’ energy metabolism and immune function. To the researchers’ surprise, these effects could still be detected after two nights of normal sleep.

Partial sleep loss is experienced by a large part of the working population, and these results suggest that they could be at an increased risk of health problems.

The inability of those suffering from partial sleep loss to perform complex tasks also has implications for safety. With this in mind, the project partners call for greater attention to be paid to the safety aspects of sleep loss, particularly for jobs where it could lead to an accident, such as transportation and the medical profession.

Using blue light as a sleep aid

Our bodies rely on external signals such as light to regulate our internal body clocks. Many elderly people suffer from sleeping problems which are caused in part by an inability to set their body clocks correctly.

The project partners discovered that the light information needed to regulate the body clock is transmitted less effectively in older people than in younger subjects. They also found that blue light is more effective than ordinary, full spectrum light at setting the body’s internal clock.

The researchers are now investigating whether blue light could be effective in helping older people sleep better by improving the regulation of their internal body clocks. Their findings could have implications for the design of old people’s homes.

The social side of sleep

The project has also revealed how social factors affect the quality of our sleep. For example, in Italy, the burden of care tends to fall on the shoulders of female family members. Interviews revealed that women caring for young children and adult children living at home slept poorly. However, the highest levels of sleep disturbance were found among women looking after elderly, frail relatives.

A survey of middle-aged British women also revealed that women with a lower socio-economic status, and particularly women with lower levels of education, are more likely to suffer from disturbed sleep.

This kind of information is essential if the project’s other findings are to be successfully transformed into practical advice for stakeholders such as the medical community.

Training up the next generation of sleep researchers

At the heart of all this research activity is a training network of 16 research fellows from 12 countries who are being given a thorough grounding in the theory and practice of sleep research. The six laboratories involved in the project cover a range of disciplines in sleep research (basic biomedical research, basic human research, circadian research, clinical research and sociological research). The students therefore have the chance to learn more than they would if they were based in a single laboratory, working in just one area. The project places a particular emphasis on ensuring that the research fellows gain experience of both social and biomedical research. In addition to research skills, the students are also taught research management, research ethics and communication skills.

For project coordinator Tarja Porkka-Heiskanan of the University of Helsinki, the importance of this research for Europe’s economy as well as its health is clear. ‘The modern society needs workers who are alert, creative and motivated throughout the day. These qualities are most easily damaged by sleep loss,’ she explains. The project partners are working hard to communicate their results to the public, so that we can all benefit from them and, hopefully, get a good night’s sleep on a regular basis.