Many people rely on caffeine to keep them going throughout the day, but imagine feeling constantly groggy despite sleeping for up to nine hours at night in addition to daily two-hour naps.
Dr Aaron Ting is a respiratory and sleep specialist who discussed what his patients mean by daytime tiredness and whether it is an indication of underlying sleep disorders.
"If people are sleeping seven to nine hours at night and needing a nap during the day, this could be attributable to a number of conditions. It depends on what other symptoms the patient presents with," Dr Ting said.
Daytime sleepiness is just one of the symptoms of sleep disorders and causes for it are many, from polymyalgia rheumatica or chronic fatigue syndrome to narcolepsy. But the terms fatigue and tiredness can be misused in the public vernacular, as they have become interchangeable with sleepiness.
"While there is a crossover of symptoms, tiredness and sleepiness are not the same thing," he said.
He gave the example of watching the TV during the day after doing some labour-intensive work.
"Those with fatigue will be able to sit and watch the TV although they are physically drained but those with excessive sleepiness will easily doze off to sleep while watching," he said.
A disorder of excessive daytime sleepiness is narcolepsy, which is a deficiency in a brain chemical called hypocretin that plays a part in regulation of the sleep-wake cycle. It can affect people in different ways.
"When sleeping they could doze off to sleep suddenly, called 'sleep attack' and go directly into deep sleep. They also experience cataplexy or loss of muscle tone when, for example, laughing or crying, which can result in a conscious collapse.
"They can also experience sleep paralysis - an inability to get out of bed. Some people encounter vivid or hallucinatory dreams either when going to sleep or upon waking," said Dr Ting.
Idiopathic hypersomnolence is another excessive daytime sleepiness disorder and mostly affects people under 30. Those with the condition can sleep for longer than usual at night, take naps of two or more hours during the day, and have trouble waking up. Often they will need multiple alarms or even other people to wake them up, when they feel 'sleep drunk' for quite a while upon waking.
"The implications of not seeking treatment are played out in their daily life through a lack of concentration and memory disturbance. They present a major driving risk. There is also the impact on their work, study and relationships," he said.
Think you might have a sleep disorder?
A sleep study to exclude a sleep disordered breathing and other sleep disorders is a good place to start if any of these symptoms sound familiar said Dr Ting. A daytime nap test called multiple sleep latency (MSLT) is an objective test to assess the degree of daytime sleepiness in these patients.
"If people are using a lot of stimulants to stay awake and are having trouble sleeping, they should make an appointment with their GP to discuss their disrupted sleep patterns," he said.
Dr Ting said they should be honest with their GP about how much caffeine and other substances, such as alcohol they are consuming. A sleep diary (such as these templates from Sleep Australia) is an excellent resource for helping your clinician understand your sleep and daily functioning levels.
Treating idiopathic hypersomnolence takes into account how much the condition affects the person's life. Stimulant medication might be prescribed.
"Studies have shown the timed consumption of caffeinated drinks can counter daytime sleepiness in those who have acceptable sleep patterns with adequate sleep. However, the advice is not to drink alcohol, smoke cigarettes or consume caffeine four to six hours before sleep," he said.
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