There has been a modest reduction of sleep time in modern civilisation, due to expectations from family and social changes, as well as work commitments or extra-school curriculum.¹

“Mammalian sleep is closely integrated with the regulation of energy balance and metabolic survival of the organism.”²

Five factors that are influenced by sleep deprivation:

1. Fatigue & hunger

Sleep loss is closely associated with fatigue the following day.³ A single night of sleep deprivation leads to increased levels of a hormone called ghrelin, which increases appetite. Less sleep can trigger elevated levels of ghrelin, which will increase hunger. Long term sleep deprivation can lead to weight gain and obesity.⁴

2. Increase in inflammation

Inflammation is a biological response to protect and heal the body against damage to cells, irritants, or pathogens. Unfortunately, it is also a painful process.

A night of total sleep loss has shown an increase in proinflammatory cytokine IL-6 the following day.⁵ IL-6 is a marker of systemic inflammation. However, long term (chronic), inflammation may lead to insulin resistance, cardiovascular disease, and osteoporosis.⁶

3. Impaired glucose metabolism

Glucose is required as an energy source for the brain and red blood cells as part of normal functioning. Glucose is stored in the liver as glycogen and when the blood glucose concentration is low, glycogen is converted to glucose in order to regulate the glucose levels in the blood. Starvation and intense exercise are examples of situations that lower the glucose concentration.

A study published in the Journal of Lancet reported that:

“Sleep restriction to 4 hr/day for 6 days was associated with significant impairment of glucose metabolism.” ⁷

4. Muscle

Interestingly, Mr Dattilo, a researcher from the Department of Psychology, Federal University of São Paulo and his colleagues hypothesised that:

“Sleep debt decreases the activity of protein synthesis pathways and increases the activity of degradation pathways, favouring the loss of muscle mass and thus hindering muscle recovery after damage induced by exercise.⁸

5. Decreased performance

Modest sleep loss (2 hours less/night) has been associated with impairment of psychomotor performance in adults. In a study published in the Journal of Clinical Endocrinology and Metabolism, psychomotor was analysed with the Psychomotor vigilance task (PVT), which is a test of behavioural alertness. It is a simple reaction time test to evaluate sustained-attention and response in a timely manner. Speed of reaction to a visual stimulus was measured.⁹

Sleep deprivation correlates with deteriorated alertness, slower problem-solving skills, and declined psychomotor skills.

Conclusion

Sleep deprivation is more than just feeling tired. Think twice before you decide to stay up late before for an exam, sports participation, trying to lose weight, or for general health. If you cannot sleep (insomnia) get assessed by your doctor. Humans are not created to never sleep.

1.National Sleep Foundation 2002 (2002). sleep in America poll. Washington DC: National Sleep Foundation.
2.Siegel JM (2005). Clues to the functions of mammalian sleep. Nature; 437(7063):1264-71.
3.Feinberg I, Gloyd TC, March JD (1991). Acute deprivation of the terminal 3.5 hours of sleep does not increase delta (0–3 Hz) electroencephalograms in recovery sleep. Sleep,14:316-319.
4.Schmid SM, Hallschmid M, Jauch-Chara K, Born J, Schultes B. (2008). A single night of sleep deprivation increases ghrelin levels and feelings of hunger in normal-weight healthy men. J Sleep Res.;17(3):331-4.
5.Vgontzas AN, Papanicolaou DA, Bixler EO, Lotsikas A, Zachman K, Kales A, Prolo P, Wong ML, Licinio J, Gold PW, Hermida RC, Mastorakos G, Chrousos GP. (1999). Circadian interleukin-6 secretion and quantity and depth of sleep. J Clin Endocrinol Metab.;(8):2603-7.
6.Vgontzas AN, Bixler EO, Papanicolaou DA, Chrousos GP (2000). Chronic systemic inflammation in overweight and obese adults. JAMA 283:2235–2236
7.Spiegel K, Leproult R, Van Cauter E (1999). Impact of sleep debt on metabolic and endocrine function. Lancet 354:1435–1439
8.Dattilo M, Antunes HK, Medeiros A, Mônico Neto M, Souza HS, Tufik S, de Mello MT. (2011). Sleep and muscle recovery: endocrinological and molecular basis for a new and promising hypothesis. Med Hypotheses. 2011 Aug;77(2):220-2.
9.Vgontzas AN, Zoumakis E, Bixler EO, Lin HM, Follett H, Kales A, Chrousos GP (2004). Adverse Effects of Modest Sleep Restriction on Sleepiness, Performance, and Inflammatory Cytokines. J Clin Endocrinol Metab;89 (5): 2119-2126.