Types of sleep disorders


There are three broad groups of sleeping disorders. These can be primary sleep disorders or secondary to other medical conditions or treatments or substances :

1. Insomnia
2. Hypersomnia
3. Parasomnia

Insomnia is the sleep disorder most of us might experience; it is the feeling that you haven’t had enough sleep because you couldn’t get to sleep in the first place, or woke up frequently during the night or woke up early. You will also wake up feeling tired, sluggish and unrefreshed – what’s more, you’ll probably find you have problems functioning during the day too.

As we age, our need for sleep reduces as our sleep patterns naturally change. Older and elderly people can find that they sleep earlier in the evening and wake much earlier the next morning than in their 20s or 30s. In fact the highest level of insomnia happens in people aged 65 years and over.

There are two types of insomnia; primary, where the loss of sleep is the main problem and your inability to sleep is caused neither by a physical nor mental illness, or results from the side effects of medication you might be taking, or indeed is caused by street drugs. Secondary insomnia happens when your sleep problems are caused by another factor. Being unwell, the side effects of medication or perhaps being depressed, anxious or worrying about something can all contribute to secondary insomnia.

Insomnia can be transient lasting less than a fortnight; short-term lasting less than three weeks, or chronic lasting more than three weeks.

Transient or short-term insomnia is often linked to something that’s happening in your life, such as anxiety or stress about something in your life, and once that situation is sorted out, the insomnia often passes. Examples might be preparing for an exam, waiting for test results, or starting new medication. In some people, the short-term insomnia triggers anxieties about getting to sleep and this can contribute to chronic insomnia.

Chronic insomnia can be a primary disorder or secondary to another medical condition.

You may have primary insomnia if:
• Your main complaint is difficulty falling or staying asleep, or feeling unrefreshed the next day after
• a night’s sleep, for at least one month or more;
• Your sleep disturbance (or the daytime sleepiness that results from it) is worrying you, hindering
• your day-to-day activities, or affecting your relationships;
• Your sleep disturbance is not linked to other sleeping problems such as narcolepsy, sleep
• apnoea, circadian rhythm sleep disorder, or a parasomnia;
• Your sleep disturbance is not linked to mental health problems like depression or anxiety;
• Your sleep disturbance is not a side effect of medication, substance abuse like alcohol or illegal
• street drugs, or an underlying medical condition.

Hypersomnia
Excessive need for sleep (hypersomnia) may be the result of a sleep disorder and is often the result of lack of sleep at night. The reasons you might not be getting enough sleep may be varied; a medical condition, environmental influences like living next to a noisy road, looking after a baby, burning the candle at both ends and so on. Sometimes, however, daytime sleepiness may be part of a medical condition like narcolepsy, a primary sleep disorder where you have frequent episodes of excessive sleepiness during the daytime, alongside complete or partial loss of muscle tone.

Parasomnia
Parasomnia is difficulty waking up and there are a number of primary sleep disorders that come under this heading, all linked with difficulties in the transition from sleep to wakefulness. The best-known one is sleepwalking but this category includes people who act out dreams while still asleep, sleep drunkenness, and night terrors.

References

Kandel ER, Schwartz JH, Jessell TM. Principles of neural science. © The McGraw-Hill Companies Inc, 2000

Ancoli-Israel S, Roth T. Characteristics of insomnia in the United States: results of the 1991 National Sleep Foundation Survey. 1. Sleep 1999; 22 (Suppl 2): S347–S353

National Institute of Mental Health. Consensus conference report: drugs and insomnia –the use of medication to promote sleep. JAMA 1984;251: 2410–2414.