Written by :
Honorary Professor of Neurology,
BJ Medical College, Pune
Sleep is essential for the normal functioning of the human body. The duration of essential sleep varies from one individual to another. Some people may feel fresh and energetic after 6 hours of sleep while others may need to sleep for 8 hours Babies need most sleep and may sleep for almost 16 hours a day. Teenagers need an average of 9 hours, and for most adults, an average of 8 hours of sleep a day suffices.
Though the amount of sleep needed remains constant with increasing age, older people tend to sleep less. This is particularly noticeable in males. Older females tend to sleep as long as younger ones. Older people also spend less time in deep sleep than younger people.
What are the various stages of sleep?
There are five stages of sleep ranging from the lightest to the deepest sleep. When someone sleeps, he goes through stages 1,2,3,4 and REM (rapid eye movement) sleep. During the first four stages, a person gradually drifts from light sleep to very deep sleep. During the fifth stage, sleep again starts becoming lighter and eye movements begin. In the first stage, the person can be woken up easily. The brain activity does not slow down. In the second and third stages, the individual goes into deeper sleep. The brain activity slows down and eye movements stop completely. The fourth stage is the stage of complete deep sleep. Most sleepwalking and bed wetting
occur in this stage. There are no dreams in this stage.
It is during the fifth stage of REM sleep that a person dreams. The eye movements begin and the body muscles become tense. Breathing becomes rapid and brain activity increases. There is also a rise in blood pressure.
What are sleep disorders?
Any condition that causes a disturbance in sleep or due to which an individual is unable to complete his quota of required sleep is called a sleep disorder. The main types of sleep disorders are – sleep apnoea, narcolepsy, restless legs syndrome and insomnia.
- Obstructive sleep apnoea – this is the most common form of sleep disorder which may usually be ignored as excessive snoring. Sleep apnoea is a disorder of disrupted breathing during sleep. The throat muscles relax during deep sleep. In persons with sleep apnoea, the muscles relax so much that they cause obstruction to the windpipe making breathing difficult. In some cases, the breathing may actually stop for sometime. The patient may wake up at this time but does not remember it afterwards.
The symptoms of sleep apnoea include heavy snoring, drowsiness during the day due to disturbed sleep, headaches on waking up, decrease in muscle coordination and in the long run, mood changes and depression. The sleep apnoea syndrome is one of the commonest causes of excess daytime drowsiness. When the patient tends to fall asleep inappropriately eg. during conferences, while talking, while eating or while driving. If such a patient also gives a history of loud and heavy snoring and is obese in weight, clinical suspicion of sleep apnoea is very high. A sleep test called polysomnography is usually done to diagnose sleep apnoea. A polysomnograph measures eye movement, heart rate, breathing rate, brain waves and muscle tension. The test is not painful.
Sleep apnoea syndrome is diagnosed if there are at least 7 episodes of apnoea (stoppage of breathing associated with fall in blood oxygen) per hour of sleep, Sleep apnoea syndrome tends to cause Hypertension, heart disease, heart attack and strokes. Besides it may lead to accidents if patients persist in driving.
Treatment - Some changes in the sleeping position may bring about relief from the symptoms. Sleeping on the side instead of the back and reducing weight if obese may help to alleviate the condition. Many such patients also have low thyroid function and this should be looked for and corrected. In the past sleep apnoea was treated by doing a tracheostomy or making an opening in the lower part of the wind pipe so that even if the upper airway obstructs, breathing continues. Sometimes surgery was done to increase the area of the air passage. Now we believe that if air is given at high pressure into the back of the nose it will prevent the air passage being occluded. This is done by putting the patient on a machine (BIPAP), which delivers air at pressure into a mask fitted snugly on the nose. This is used each night. Patients definitely become more active after using the machine.
- Narcolepsy – it is a disorder of abnormally increased sleep. People with narcolepsy have irresistible sleep attacks during the day. These are different from “catnaps” that are voluntary naps taken by people. Narcoleptic attacks may occur anytime during the day even when the individual is engaged in some activity. These attacks last from less than a minute to more than half an hour. The sleep pattern during this time is also abnormal. The patient enters the REM stage of sleep prematurely. The duration of time spent in the stage of deep sleep is also less.
Other symptoms of a narcoleptic attack include muscle twitching and stiffness of muscles (cataplexy), sleep paralysis (involuntary numbness and immobility of limbs) and dream-like hallucinations while awake. The person may fall asleep while involved in an activity like driving which can be extremely dangerous. Frequent attacks of narcolepsy generally indicate severe sleep deprivation.
Narcolepsy is usually a genetic disorder and thus requires medical treatment. In some people it may be due to a brain disorder or a neurological problem. Narcoleptic attacks may be more common in conditions like pregnancy, fever, increased stress and fever. When examined by Polysonography patients of narcolepsy start often with a REM sleep and may have dreams and excess movement during stage 3 or 4 sleep. The sleep latency i.e. time from trying to sleep to falling asleep is shorter implying there is a disruption of entire sleep function. Narcolepsy is also then a cause of excess day time drowsiness and should be suspected in such patients if:
- There is no obesity or no excess snoring and
- If there is associated cataplexy or sleep paralysis.
- Besides sleep apnoea and Narcolepsy other causes of excess day time drowsiness are
- Metabolic disorder like renal failure, liver failure or lung disease causing hypoxia.
- Excess use of sedatives
- Alcohol abuse and some brain tumours.
- Some drugs not considered sedatives also some times cause drowsiness e.g. anticonvulsants.
There is no known cure for narcolepsy. Treatment involves some lifestyle modifications that may help to alleviate the symptoms. Regularising the sleeping pattern helps in reducing the symptoms. Light meals should be taken at dinnertime and if possible, a short nap may be taken after every meal. In some cases, the doctor may prescribe stimulants such as dexidrine or Ritalin to reduce the attacks. Cataplexy responds well to Imepramine (Depsonil).
- Restless legs syndrome (RLS) – it is a less common disorder among the middle aged and elderly. Affected individuals experience a tingling and prickly feeling in their legs as they try to fall asleep. The feeling is usually so intense that the person finds it difficult to sleep and has to move his legs to get rid of the feeling and he may have to move his legs, press them, tie bandages round them or walk up and down the room to get relief and move the legs about. On examination there is usually no abnormality but some cases of early nerve disease e.g. renal failure and alcoholic neuropathy may start as restless legs. Many patients with restless leg have periodic leg movements even in sleep, which may disturb the partner. The best treatment for restless legs is a small dose of L Dopa and Carbidopa (same drug used in Parkinson) or Clonazepan at bedtime. Results may not always be satisfactory.
- Insomnia - Insomnia is a condition where sleep is disturbed for prolonged periods and person takes long time to fall off to sleep or having fallen asleep wakes early. The person thus sleeps less than 4 hours and suffers effects of sleep deprivation and tries all sorts of drugs to get relief. The causes of insomnia are many and include
- Psychiatric disorders including depression, anxiety, mania, agitation.
- Situational insomnia due to pain, discomfort, heart failure, or restless legs. Arthritis patients and chronic bronchitis patients often have insomnia
- Other sleep related illness like carpal tunnel syndrome causing tingling in the hands
- Some drugs may disturb sleep such as fluoxitane, ciprofloxacin, theophyllin etc.
- Primary insomnia where none of these apply and people go long periods with insomnia.
- A rare new disease fatal familial insomnia. Which is a rare disorder caused by abnormal genetic material a prion protein. In the vast majority the cause is psychogenic and the situational ones easily diagnosed.
Besides these children have a number of sleep related problems.
- Nocturnal enuresis - tendency to pass urine in sleep, in clothes. This affects 1 in 10 children between 4-14 years. In a child in whom control was never established it is usually a matter of development delay and will come under control with time. The best treatment is to use an alarm to wake the child in the middle of sleep and send him to pass urine. A useful drug is imipramine (depsonil) and gentle education. Where control over urine was established and then enuresis restarts one should look for the possibility of a spinal lesion in the lumbar region.
- Nocturnal terrors - patient gets up frightened may cry hold tight to relation and have a fast pulse and in short time settle down. It may be mistaken for epilepsy. It can occur each night.
- Sleep walking - this is not a form of epilepsy and does not imply psychiatric disorder and child may walk about at night for a while and then return and lie down. This usually clears by itself. One has usually only to ensure that the child does not hurt himself in such episodes.
What can be done about sleep disorders?
Most countries have specialised sleep clinics where people with sleep disorders are treated. These clinics have specialised personnel and equipment to diagnose the condition and carry out rehabilitation of patients with incurable sleep disorders. India, unfortunately, does not have too many specialised sleep clinics but facilities are increasing in the major cities. A patient can usually consult a neurologist for medical help.
Lifestyle changes like regularising sleep patterns, eating lighter meals, reducing weight and taking short frequent naps during the day may help. However, a doctor’s opinion should always be sought in case such a condition is detected.