Lack of Sleep Affects Hormones

Article Description: The changes in sleep quality that often come with age seem to trigger shifts in the endocrine system, altering hormone levels and metabolism. Researchers say that this study shows that a good night's sleep may be a natural form of hormone therapy, particularly for older adults.
Date of Publication: 02/27/04

• Researchers studied 149 men, aged 16 to 83, and found that age-related changes in sleep quality were linked to specific changes in several hormones.
• As sleep quality and quantity declined levels of the adrenal hormone cortisol increased, while levels of Growth Hormone (GH) declined.
• After the age of 25, men experience a decline in deep sleep that accompanied by a drop in GH production. GH deficiency is related to reduced muscle mass and strength, increased fat tissue, weakened immunity to infection, and other health declines.
• In later years, a new sleep pattern emerges, in which men get less sleep overall and levels of cortisol go up. Elevated cortisol may underlie a host of mental and metabolic problems, including memory loss and insulin resistance -- a precursor to diabetes.

• The average percentage of time spent in deep slow wave sleep decreased from 18.9% during early adulthood (age 16-25 years) to 3.4% during mid-life (age 36-50 years).
• This lost deep sleep was replaced by lighter sleep (stages 1 and 2) without other significant changes.
• The transition from mid-life to late life (age 71-83 years) involved no further significant decrease in deep slow wave sleep but an increase in time awake of 28 minutes per decade at the expense of decreases in both light non-REM (rapid eye movement) sleep and REM sleep.

• The decline in slow wave sleep from early adulthood to mid-life was paralleled by a major decline in GH secretion (-372 µg per decade).
• From mid-life to late life, GH secretion further declined at a slower rate (-43 µg per decade).
• Independently of age, the amount of GH secretion was significantly associated with slow wave sleep.
• Increasing age was associated with an elevation of evening cortisol levels (+19.3 nmol/L per decade) that became significant only after age 50 years, when sleep became more fragmented and REM sleep declined.

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