Skip navigation

VII.20. Lack of sleep

According to a study by the American Sleep Disorders Association, teenagers need a minimum of 9.5 hours sleep for normal growth and normal development of the brain and sexuality.  

By contrast, as age progresses the sleeping time gradually decreases (at 12 years of age the need is about 8 hours, while at 18 years of age it is about 6 hours).

The role of sleep:

  • defense against oxidative stress
  • maturation and development of the neurons
  • glycogen replacement into the brain
  • maturation of the brain
  • the activity of the brainstem motor system
  • a role in the formation of memory

 

During sleep, the levels of many hormones change:

At the beginning of sleep the level of GH is high in men, but in the second half of sleep and before the beginning there is a peak of sleep in women.

The level of cortisol is low in women it is higher than in men.

GHRH has an important role in the regulation of sleep: it increases the GH level and inhibits the cortisol level (but in women it stimulates the cortisol level, and depression is therefore more frequent in women).

Hormones which inhibit the GH-RH effect include Somatostatin, TSH, CRH and ACTH.

GH-RH effect is stimulated by ghrelin, galanin and VIP.

Hormones which play a role in wakening include CRH and NPY.

Hormones which play a role in the regulation of the sleep rhythm include VIP, FSH, LH (mainly in puberty), melatonin and TSH.

Since 1969, the length of the working time has increased in the USA. This has led to an increase in the problems of the lack of sleep because of the shift work schedules. 

 

Many factors can influence the length of sleep:  

genetics

age (menopause, sleep decline in old age)

obesity (40% have sleep problems)

DM (half of the patients have sleep problems)

diseases (heart problems, respiratory problems, cancer, osteoporosis, etc.)

medicaments

stress

Sleep deprivation can lead to problems:

the efficiency of the nervous system diminishes

memory and learning skills deteriorate

muscle tremor is caused by long-term sleep deprivation

depression may develop

the risk of death increases by 30% at less than 6 hours sleep per day

the thermoregulation deteriorates

the risk of obesity rises in parallel with the lack of sleep

the TSH level decreases, and hence the circadian rhythm is upset

the leptin level decreases, and the risk of obesity therefore  increases

the ghrelin level increases (enhancing food intake)

the HOMA index increases, and the insulin sensitivity decreases

the cortisol level increases (an increased appetite)