A chemical builds up in our brain making us sleepy, this switches on the sleep process. This chemical is blocked by caffeine which is why coffee and tea keep us awake.
The eye senses light which then resets our internal body clock, sending a message to our sleep center to switch on the sleep process. Our internal body clocks are genetically programmed to make us short sleepers or long sleepers.
When we first fall asleep the body starts to relax and the breathing becomes slower and deeper. Occasionally we can feel “hypnogogic jerks”, these are sudden jerks that can cause awakenings, though thy rarely prevent us from falling asleep. Sleep occurs in cycles; light sleep, deep sleep then ‘dream state’ or REM sleep. Each cycle lasts approximately 90 mins. We have three to four cycles in an average night.
If sleep is disturbed, we can compensate for a short time, but the processes for coping will eventually wear out and we will start to feel tired or sleepy during the day. Memory function decreases, resulting in more forgetfulness.
Snoring is the sound produced by the structures in the mouth and throat vibrating whilst we are breathing during sleep. Snoring can cause sleep disturbance to the individual, but often causes social problems and sleep disturbance to others around as well.
Breathing in sleep may restrict the flow of air from the nose into the lungs. If airflow restriction is severe, it can cause a sleep disturbance known as Upper Airways Resistance Syndrome.
Upper Airways Resistance Syndrome may be caused by nasal stuffiness and congestion, as well as reduction of the total space in the throat for air to flow into the lungs.
Sleep Apnoea is caused by the airway space in the mouth and throat reducing to the point at which there is no flow of air into the lungs. Each apnoea must last at least 10 seconds to be considered significant. The reduction of airflow to 50% of normal is called a hypopnoea, this must also last at least 10 seconds and cause a drop-in blood oxygen levels.
Sleep apnoea may be categorised as:
Mild 5-15 episodes per hour
Moderate 15-30 episodes per hour
Severe over 30 episodes per hour.
RESTLESS LEG SYNDROME
Restless Leg Syndrome is a condition which occurs more commonly in the over 50s. Symptoms involve unpleasant sensations in the legs when sitting at rest, which may improve upon walking and movement. Some may experience the sensation of insects crawling up the legs and find this symptom worsens in the evening. Restless leg syndrome can disrupt sleep due to repetitive leg twitches during the night. Restless leg syndrome often requires treatment.
PERIODIC LIMB MOVEMENTS DISORDER
Narcolepsy may be an autoimmune condition which may take more than 20 years to diagnose from the original episode. Narcolepsy has also been known to occur following infections such as influenza, encephalitis and glandular fever. Very rarely narcolepsy can occur after a significant head injury.
Narcolepsy sufferers find daytime naps are often needed in order to function.
A very rare form of Narcolepsy with Cataplexy is known to occur if the person finds that they collapse or suffer weakness when experiencing emotional states such as laughing and crying.
Insomnia occurs if patients cannot fall asleep or stay asleep, currently incidence of insomnia in the general population is up to 40%. Chronic insomnia may be diagnosed if sleep is disturbed three night a week or more, for three months or longer.
Insomnia has been linked with worsening health of the sufferer later in life. A number of scientific studies have linked untreated insomnia with the following:
Failure of relationships
Mental health problems
Accidents at work
Reduction in immune system functioning.
Reduced fertility and or libido
CIRCADIAN RHYTHM DISORDERS
These genes cycle over 24 hours. Timing is closely aligned to the earth’s day and night cycle by a master clock called the Suprachiasmatic nucleus.