Sleep and sleep disorders

Published on 09/04/2015 by admin

Filed under Neurology

Last modified 09/04/2015

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Sleep and sleep disorders

Sleep problems are common. Almost everyone has disturbed sleep at some time, but usually the cause is self-evident and self-diagnosed. Some patients have significant sleep problems. Most can be diagnosed from the history from the patient and their sleep partner. Sometimes further investigations are needed to confirm or clarify the diagnosis.

Background

Normal sleep

The amount of sleep which is normal varies from person to person and it is important to establish if there has been a change in a patient’s total time spent asleep. Normal sleep is divided into a number of stages, primarily on the associated EEG patterns:

Light sleep – stages 1 and 2 (55–65% of sleep).

Deep sleep – stages 3 and 4 – slow-wave sleep (10–20%).

Rapid eye movement sleep (REM sleep) (15–25%). In REM sleep, there is loss of tone in all muscles apart from the external ocular muscles which produce rapid eye movements.

Through a normal night of sleep there are repeated cycles of light to deep to REM sleep.

There are a number of normal phenomena that occur in sleep and that are usually readily recognized, such as dreams, nightmares or sleep talking. Other normal phenomena can lead to medical referral, for example hypnic jerks (or sleep starts) which are sudden movements that occur on falling asleep, or sleep paralysis which occurs when awaking during REM sleep with marked loss of muscle tone. While sleep paralysis is normal, it does occur more often in patients with narcolepsy (see below).

Taking a sleep history

Once the patient has described the problem in their own words and with as little prompting as possible, it is important to take a sleep history. Establish from patients: the time they go to bed; how long till they fall asleep; when they wake; how often they wake through the night and what they do when they wake; how they feel on waking in the morning; whether they sleep again through the day, when and where and for how long; and if and when they feel sleepy – the Epworth sleepiness scale can be used to measure the degree of daytime sleepiness. A parallel history should be taken from any sleep partner, but also asking whether they snore or move when asleep. There may be significant differences in what the patient describes and what is observed.

A number of factors can interfere with sleep (Table 1) and these factors should be explored.

Table 1 Some factors that can interfere with sleep

Factor affecting sleep	Effect
Previous sleep history	Helps determine ‘normal’ amount of sleep for that person
Work pattern/domestic circumstances	Long hours or shift work may disrupt sleep Babies or young children or partner may cause repeated awakenings
Exercise	Has an alerting effect but aids sleep if exercise is earlier in the day
Psychiatric history	Anxiety – makes going to sleep more difficult Depression – results in early morning waking
Alcohol	Makes people sleepy but reduces sleep quality
Caffeine	May cause difficulty going to sleep
Medication	Most cause sedation
Pain, arthritis, carpal tunnel syndrome	Lead to recurrent awakening
Nocturia	Recurrent awakening
Daytime naps	Reflect daytime sleepiness but may also contribute to difficulty sleeping at night

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