Having trouble getting a good night's sleep lately? Maybe you're having trouble staying awake during the day. Well, you've got plenty of company.

According to figures released by Statistics Canada in 2002, one in seven Canadians over the age of 15 — or around 3.5 million people — have difficulty falling sleep or staying asleep. The data — from the Canadian Community Health Survey — suggest that about 18 per cent of those people average less than five hours of sleep a night.

The U.S. National Sleep Foundation says teens need 8.5 to 9.5 hours of sleep a night while adults should get seven to nine hours.

A lot of people can get by with less than the recommended daily dose of sleep — but if insomnia regularly makes it difficult for you to get through the day, you have a problem.

Insomnia can be caused by a number of factors, including:

  • Stress.
  • Nicotine, caffeine and alcohol.
  • Anxiety or depression.
  • Shift work.
  • Poor sleep habits.
  • Not getting enough exercise.
  • Medications and medical conditions.

Insomnia falls into the broad category of sleep disorders called dyssomnias, which are sleeping disorders that interfere with our quest for a good night's rest. Other types of dyssomnias include:

Narcolepsy, characterized by excessive daytime tiredness, even after adequate sleep at night. People suffering from narcolepsy may fall asleep several times during the day — with little or no warning. There are an estimated three million people worldwide who are believed to have narcolepsy. While treatment is tailored to the individual, it often includes a group of drugs that stimulate the central nervous system.

Restless leg syndrome. This condition is characterized by an irresistible urge to move the limbs to relieve uncomfortable sensations. It's most often felt in the legs, but can also affect the arms and torso. Some people only experience the symptoms at bedtime, while others deal with it all day long. Most sufferers experience the worst symptoms in the evening, while winding down from the day. There's no known cause for the syndrome, although 60 per cent of people suffering from it have relatives with the same problem. It's mainly treated with drugs.

Sleep apnea. Do you or your sleeping partner snore loudly? Sleep apnea could be the culprit. People who suffer from sleep apnea sometimes make "gasping" or "snorting" sounds when they sleep. They are prone to pauses in breathing during sleep. A little bit of sleep apnea might not be a problem — but obstructive sleep apnea can be serious. Common symptoms include loud snoring, restless sleep and daytime sleepiness. Diagnosis usually follows a night in a sleep clinic. Obesity is a key risk factor. In some cases, losing weight, quitting smoking, avoiding alcohol or using muscle relaxants may help. In more serious cases, symptoms can be relieved through "continuous positive airway pressure." You hook yourself up to a machine with a mask at bedtime and it helps you breathe properly as you sleep. And your sleeping partner will be spared your loud snoring.

Circadian sleep rhythm disorder. You sleep well — but just not when everyone else does. Your body clock is out of sync with what's accepted as normal. Types of circadian sleep rhythm disorders range from jet lag to non-24-hour sleep-wake syndrome, where your sleep occurs later and later every day and your period of peak alertness continually shifts. Most people respond to environmental time cues: sunrise, sunset and a normal routine.

Another broad category of sleep disorders has little to do with the ability to fall asleep or stay asleep. Parasomnias disrupt the sleep process in odd and sometimes dangerous ways. They can include anything from bedwetting to sleepwalking to sexsomnia. Most parasomnias are dissociated sleep states — like sleepwalking — that are partial arousals that occur during transitions between being awake and deeper levels of sleep.

Sleepwalking (or somnambulism) is more common in children than in adults, although four per cent of adults may do it. It usually happens within the first couple of hours of sleep. Most episodes normally last just a few minutes. Fatigue, stress, anxiety and fever are factors that can contribute to sleepwalking, as are conditions such as panic attacks and post-traumatic stress disorder. Sleepwalking usually does not need to be treated — unless it leads to excessive daytime tiredness or poses a risk of serious injury. If someone in your house is sleepwalking, gently lead him or her back to bed. It's all right to wake them up, but they may be confused or disoriented.

Night terrors occur in some children — usually between the ages of four and 12 — about two or three hours after the child goes to sleep. Your child may scream out, sit up in bed, thrash about or run around the bedroom or the house while still asleep. Your child may resist if you try to hold or comfort them. Episodes normally last for a few minutes and the child generally wakes with no memory of the incident. Treatment is rarely necessary.

Bruxism — or teeth grinding — is one of the most common sleep disorders. It can be caused by stress, drinking, some medications, obsessive-compulsive disorder and smoking. Symptoms include morning headaches, jaw pain, earache, facial pain and neck, shoulder or back pain. It can also do serious damage to your teeth. Most people with the condition aren't aware of it and only five per cent go on to develop symptoms. There's no known cure, but there are several treatments. Your dentist may recommend a mouth guard or splint to keep your from griding your teeth.

Sexsomnia — similar to sleepwalking — is a dissociative state that causes people to engage in sex acts while fast asleep. It was first identified by researchers at the University of Toronto in 1996. Symptoms range from loud, disruptive moaning to violent sexual acts. As in sleepwalking, people have no memory of the event when they wake up in the morning. Researchers believe that episodes can be triggered in some people when they do not move smoothly from one level of sleep to the next. A study published in the June 1, 2007, edition of the journal Sleep found that people who suffered from sexsomnia had two to four other sleep disorders, from sleepwalking to sleep terrors. Therapy can include medication as well as treatments for breathing disorders.