The internal clock in living beings that regulates sleeping and waking patterns - usually called the circadian clock - has often befuddled scientists due to its mysterious time delays. Molecular…

There are several aspects of the costs of sleep disorders to society.

1 Development of other diseases which could have been avoided if the sleep disorder had been recognized and treated earlier. An…

Sleep occupies approximately 8h of each 24-h cycle, but much less attention has been paid to the medical problems during this phase of life than to those that occur during wakefulness.

There are…

It is common for there to be a prolonged episode of wakefulness before take-off on space travel. There may be as long as 30h of continuous wakefulness before sleep is first obtained during…

Disrupted sleep at night is often the cause of elderly people requiring long-term residential and nursing home care, but the environment that these institutions provide frequently exacerbates the sleep disruption.

Lack…

Most people fall asleep more readily and sleep more soundly in familiar surroundings, except those with psychophysiological insomnia. This is exemplified by the ‘first night’ effect in the sleep laboratory, which is characterized by…

Behavioural treatments
These include cognitive behavioural therapy which aims to alter attitudes about comfort eating, and anxiety about lack of food availability and the moral duty to finish…

Obesity is related to the following sleep conditions.

Sleep deprivation and fragmentation
Sleep deprivation and fragmentation lead to insulin resistance and other hormonal and autonomic changes with the result that appetite is…

Sleep disorders may affect the bed partner, family, friends, carers and even neighbours in addition to the patient. The partner may become concerned because of the implications of the sleep disorder, especially when…

The control of sleep is closely linked to feeding behaviour and energy expenditure. These determine the body weight and in particular the body fat and lean body mass. Body weight and body mass index…

Intrusion of REM into NREM sleep does not cause any symptoms because sleep is maintained, but is very common. Muscle atonia, which is characteristic of REM sleep, is seen in NREM…

Mixed and transitional states are very variable, but can be categorized according to the state in which they arise.

Wakefulness
Sleep inertia is the drowsiness, often associated with physical incoordination and occasionally with…

Sleep and wakefulness are not totally distinct states.

The constant flux in the activity of many parts of the brain may lead at any one time to either an over-whelming balance of activity in…

A rest–activity pattern is detectable in almost all organisms and this may be related to the presence of clock genes which have been largely conserved throughout evolution. Whether or not these…

External influences and some internal stimuli have less influence on the brain during sleep than during wakefulness. To an extent the brain becomes deafferentated, and partially deprived of sensory stimulation. This has…

Sleep is recognizable by its contrast to wakefulness.

It is a state of reduced awareness and responsiveness, both to internal and external stimuli. This reduced awareness is, however, selective [1]. It is an…

Sleep disorders still often remain unrecognized and untreated despite the rapid advances in the understanding of their nature over the last few years.

Sleep medicine as a specialty is only…