Importance of Sleep

Along with diet and exercise, the quality and quantity of sleep a person gets greatly influences their quality of life.

Physiological Effects of Sleep

Although sleep is still not completely understood, studies demonstrate that it is an active physiological state during which the body repairs itself and performs a variety of important functions. Studies have shown that sleep affects:

  • Learning and Memory

    Sleep is important for consolidation of new information and memory formation.

  • Growth and Development

    Secretion of growth hormones and prolactin is increased during sleep.

  • Blood Pressure

    Chronic short sleep duration increases the risk of hypertension in adults.

  • Stress and Metabolism

    Levels of cortisol and thyrotropin (thyroid stimulating protein) decrease during sleep.

  • Appetite Management

    Sleep affects levels of ghrelin and leptin, hormones that influence feelings of hunger and satiety.

Consequences of Sleep Deprivation

Individuals exhibiting normal sleep patterns will generally sleep 7-8 hours per night. Numerous studies indicate that individuals who routinely experience fewer than 6 hours of sleep per night, whether voluntarily or involuntarily, often suffer physiological and emotional consequences, including:

  • Increased risk of cardiovascular disease
  • Obesity
  • Depression
  • Memory loss

The National Sleep Foundation estimates that the annual costs associated with sleep deprivation and sleep disorders in the US, including medical expenses, sick leave, and lost productivity, exceed $100 billion.

Sleep and Type 2 Diabetes

Studies show that sleep deprivation may increase the risk of obesity and type 2 diabetes.

  • Several epidemiological studies report a correlation between short sleep duration and higher mean BMI and/or obesity.1
  • Studies of young, healthy males show that sleep deprivation over as few as two nights results in decreased glucose tolerance and increased appetite for carbohydrate-rich foods.2,3 The observed increase in hunger, if translated into actual ingestion of the desired foods, would correlate to an excess of 350-500 kcal/day.
  • Longer term studies suggest that chronic sleep deprivation may result in reduced insulin sensitivity.1
  • Population studies indicate that chronic short sleep duration is correlated with an increased risk of type 2 diabetes or impaired glucose tolerance, after adjusting for potential confounding effects including age, sex, BMI, and waist circumference.4,5,6

Sleep apnea disrupts sleep by causing sleep fragmentation and recurring intermittent hypoxia. Read more.

Dr. Aliya Ferouz Colburn on The importance of sleep

1 For review, see Van Cauter E, et al. Horm Res 2007;67 (suppl.1):2-9
2 Spiegel K, et al. Lancet 1999;354:1435-9
3 Spiegel K, et al. Ann Intern Med 2004;141:846-50
4 Gottlieb DJ, et al. Arch Intern Med 2005;165:863-8
5 Ayas NT, et al. Diabetes Care 2003;26:380-4
6 Yaggi HK, et al. Diabetes Care 2006;29:657-61