Cramming up through the night before an exam does more harm than good, with a new study establishing that adequate sleep is essential for learning and memory consolidation. Truncated sleep impairs the brain’s ability to learn and store new information and create memories, reported Neuron, with short-term memory taking the hardest hit.
A sleepless night or a spell of insomnia is all right as long as it doesn’t make you doze off at the wheel, say experts. “Chronic sleeplessness, however, can cause health problems as varied as reduction in memory, concentration and problem-solving capabilities to hypertension, heart disease, obesity, mood disorders and frequent infections. Some studies have even linked truncated sleep with cancers and insulin resistance (difficulty metabolising glucose), which over a period of time leads to adult onset type-2 diabetes,” says Dr Manvir Bhatia, head of sleep medicine at Ganga Ram Hospital.
In the new obsession with diet and fitness, the importance of adequate sleep is often overlooked. “Most people don’t realise that chronic sleep debt stresses the body physically and mentally, thereby increasing almost all the risk factors for heart disease and stroke, such as blood pressure, inflammation, obesity and diabetes,” says Dr J. N. Pande, senior consultant of internal medicine, Sitaram Bhartia Institute of Medical Sciences.
Sleep loss also lowers a person’s ability to handle the day-to-day stress, leading to irritability, impatience, inability to concentrate and moodiness.
Few days ago, a US study reported that circadian rhythms — the body clock —regulate metabolism and energy levels in cells and adequate sleep and a healthy diet help maintain the critical balance. This, said researchers from the US National Institutes of Health and the University of California in Science Express, partly explained why disruption of sleep patterns increase hunger and cravings, causing obesity.
Chronic sleep deprivation can alter metabolic functions, such as processing and storage of carbohydrates, and by stimulating the release of excess cortisol, a stress hormone. Excess cortisol has been linked to increased abdominal fat, another risk factor for heart disease and diabetes.
Loss of sleep also reduces levels of leptin, a hormone that suppresses appetite, and increases levels of ghrelin (grell-in), an appetite-stimulating hormone — a combination that can encourage eating, say experts.
The amount of sleep needed varies with people, with some managing on just a few hours of sleep and others barely functioning without eight to nine hours. “Most guidelines say that increased risk for diseases creep in if you are getting less than five hours and more than eight hours of sleep every day,” says Dr Bhatia.