Normal sleep patternsHuman beings need normal sleep for their physical and mental wellbeing. Most adults sleep 7-8 hours per day usually at night.The time and duration of sleep may differ in people depending on their age and health. Children sleep considerably more than older people. Majority of adults sleep only during the night for 7-8 hours whereas some divide their sleep into two parts - an afternoon nap and night sleep. Irregular sleep is normally observed in the extreme age groups such as infants and in older people.Human brain comprises two circuits - one is the arousal circuit which keeps a person awake and second is the sleep-promoting circuit which leads to sleep. The relation between these circuits is like a switch.When the switch is 'on', a person is awake and when the switch is 'off', a person sleeps. This sleep-wake cycle is regulated by the circadian rhythm of the human body. Circadian rhythm is the internal body clock of a person that regulates the external 24-hour process of the body.Importance of sleepSleep plays an important role in keeping fit and prevents many health conditions. Disturbed sleep and daytime sleepiness may affect metabolism and may lead to weight gain, irritability, forgetfulness and depression. In rare cases, people may also talk or walk while sleeping and grind their teeth. The Institute of Medicine has declared sleep deficiency and sleep disorders as 'an unmet public health problem'.Lack of sleep in the long term increases the risk of-•\tCognitive disturbances•\tGlucose intolerance and Diabetes•\tObesity•\tHigh blood pressure•\tImpaired immunity•\tPlaque build-up on the walls of the arteries•\tHeart disease and stroke Sleep disordersInsomniaInsomnia is one of the commonest sleep abnormalities. Many people complain of difficulty in initiating sleep or maintaining a normal sleep. It is more commonly observed in people as they age.Insomnia affects the quality of life of individuals. Due to a poor quality of sleep, people suffering from insomnia experience tiredness, irritability, depression and daytime headaches. Many factors contribute to insomnia. Many people with insomnia may be suffering from an underlying psychiatric disorder. Medical conditions leading to constant pain, breathing difficulty and cough may also cause sleeplessness.Obstructive sleep apnoea (OSA)Patients diagnosed to have Diabetes, hypertension and obesity are more likely suffer from obstructive sleep apnoea. The symptoms of OSA are snoring at night, daytime dozing, excessive daytime sleepiness, early morning headache, tiredness, etc. In people suffering from OSA, there is complete or partial obstruction in the upper airway. OSA leads to shallow or paused breathing. This is due to decreased muscle tone in the neck.To explain this with a practical example: Imagine an empty plastic bottle, if we close the mouth of bottle and pull the bottle base down the bottle will collapse. Similarly when the upper airway is blocked and diaphragm muscle (muscle separating thorax and abdomen) moves down, this leads to a condition mimicking minimal lung collapse which leads to decreased oxygenation of blood.In OSA, our body stores fat, our blood sugar levels and blood pressure increases and as a result there is increased risk of heart disease. It becomes difficult to manage Diabetes in people who have associated severe OSA as this also leads to severe insulin resistance. Sleep study helps diagnose OSA. Treatment of OSA improves wellbeing and is rewarding in long term.Restless leg syndrome (RLS)Restless leg syndrome (RLS), also known as Willis-Ekbom disease, is a disorder of the nervous system which causes a strong urge to twitch and shake legs intermittently. It causes an unpleasant sensation in the calves, feet and thighs. As these symptoms cause sleep disturbance, most people with RLS may experience daytime sleepiness. It is more commonly seen in women and in older adults. Consumption of alcohol, caffeine, antidepressants, a presence of iron deficiency and kidney disease may further worsen the condition. Iron deficiency is a common treatable cause of RLS.NarcolepsyNarcolepsy is excessive daytime sleepiness due to inability to regulate sleep-wake cycle. People might experience dream-like hallucinations at night, sudden loss of muscle strength when they are awake. An individual laughing at a joke may suddenly collapse on the ground in an awake and immobile situation. This condition called cataplexy is triggered by strong emotions. Sleep study helps diagnose such conditions and can be relieved by doctor consultation and timely medical intervention.Troublesome triadThere is a significant overlap between diabetes, heart disease and sleep disorders as shown in figure below-Insomnia and DiabetesThere is a direct relationship between the quality of sleep and blood sugar control in people with Type 2 Diabetes. Studies have shown that sleep deprivation leads to insulin resistance which leads to high blood sugar levels. If a person does not have a good night's sleep then glucose is released from the liver. This leads to an increase in the fasting blood glucose level. When insomnia is treated resulting in improved sleep, the person with Diabetes also has better blood sugar level control. People with Type 2 Diabetes. Studies have shown that sleep deprivation leads to insulin resistance which leads to high blood sugar levels. If a person does not have a good night's sleep then glucose is released from the liver. This leads to an increase in the fasting blood glucose level. When insomnia is treated resulting in improved sleep, the person with Diabetes also has better blood sugar level control.OSA and heart disease riskPeople with OSA have an increased risk of heart disease and stroke. Low oxygen in the blood caused by an obstruction of airway leads to inflammation, increased heart rate and increased rate of atherosclerosis leads to blockages in the arteries. Adequate and good quality of sleep is essential to reduce the risk of heart disease.Diabetes and sleep disordersPeople with Type 2 Diabetes are at an increased risk of developing sleep disorders. This could be due to associated comorbidities like obesity, hypertension or also could be because of associated complications of Diabetes like heart disease, kidney disease. Certain sleep disorders like OSA, insomnia and restless legs syndrome are diagnosed more frequently in people with Diabetes as compared to those who don't have Diabetes.Sleep studyPolysomnography (or sleep study) is a test used to diagnose sleep disorders. It records the brain waves, the level of oxygen level in the blood, heart rate and breathing, as well as eye and leg movements during the sleep. Polysomnography test continuously monitors the different stages of sleep and sleep cycle and is reported by a sleep specialist. It provides information to the physician about the quality of a person's sleep and the reason for disturbed sleep.There are mainly two stages of sleep:1) Non-rapid eye movement (NREM) sleep divided between N1, N2, N3 stages2) Rapid eye movement (REM) sleep and Stage N1 - This first cycle of sleep is described as drowsiness. Eyes are closed during Stage 1 sleep. A person can be awakened very easily, but may feel as if they haven't slept at all.Stage N2 - This is a light stage of sleep. Spontaneous periods of muscle tightening and muscle relaxation are reported. The heart rate slows and body temperature decreases. This helps to prepare the body for deep sleep.Stage N3 - This is the deep sleep stage also known as slow-wave or delta sleep. During N3 sleep the body heals and repairs itself.The first episode of Stage N3 lasts from 45-90 minutes.REM cycle - Intense dreaming occurs during the REM cycle. The first period of REM sleep typically lasts about 10 minutes. The final REM stage lengthens up to an hour. Most people spend around20 per cent of their sleep time in REM cycle.When to visit a doctor?Insomnia or sleeplessness may occur due to many reasons. It is important to first look out for the reason to sleeplessness. Simple modifications in lifestyle, regular exercise and sleep and wake up timings may help resolve insomnia in many people. If the sleep disturbances are persistent and are affecting the quality of life then it is advisable to consult a sleep specialist. The specialist may first counsel you and try to understand your daily schedule and lifestyle. You may also be recommended sleep study to understand in more detail your sleep pattern. Inform your doctor about your medications as certain medications may also cause disturbed sleep.