Why do we need sleep?
Sleep is vital for survival and the functions of many organ systems are linked to it, including the endocrine, immune, cardiovascular, metabolic and nervous systems. Studies suggest that sleep performs a crucial role in bodily restoration, energy conservation and memory function.
Below are several examples of how sleep deprivation can impact daily functioning and health:
Mental health: Sleep is thought to have an important impact on intellectual performance, with many studies suggesting a 15% improvement in memory and mental ability after a good night’s sleep2. Poor sleep is associated with higher risk of dementia-particular Alzheimer’s Disease
Obesity: A growing body of research suggests a link between sleep deprivation and obesity. One study found that sleep deprived individuals had 15% more of the hormone ghrelin, an appetite stimulating hormone, and 15% less of leptin, an appetite suppressor3.
Hormonal systems: A lack of sleep may lead to decreased glucose tolerance, a possible precursor of type 2 diabetes4. Many hormones are secreted during sleep, including human growth hormone, cortisol and sex hormones such as luteinizing hormone (LH) and follicle stimulating hormone (FSH)
Immune system: Lack of sleep is believed to weaken the immune system, making us more vulnerable to a range of illnesses from the common cold to more serious conditions such as cancer. Restorative powers are also affected; one study showed wound healing was slowed by lack of sleep5.
Cardiovascular: There is evidence to suggest poor sleep is connected to hypertension and cardiovascular morbidity such as heart failure and stroke2.
Many medical conditions affect our sleep, e.g. psychiatric and neurological disorders including depression, anxiety and pain. Parkinson’s and Alzheimer’s diseases are frequently associated with insomnia, although there is no currently proven causal relationship.
It is not surprising that sleep is important, but still most people don’t get enough sleep or good quality sleep. Our busy life of staying awake all night to study, work, or have fun is accepted and even promoted by our society, but the insufficient sleep carries with it both short and long-term consequences8.
Poor sleep also increases the risk of accidents. Drowsiness in sleep-deprived drivers causes more than 100,000 crashes, 71,000 injuries and over 1,500 deaths each year and in the U.S, while 52% of accidents involving heavy trucks were related to driver fatigue!6 7