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Chapter 15: Special Topics
15
Some important factors affecting bone health don't fit neatly into other chapters. Here are three you should know about.
Sleep and Bone Health
Most people don't connect sleep with bones, but there's a real relationship.
Why sleep matters: Bone remodeling follows a daily rhythm. Your body does much of its repair work during sleep. Chronic sleep deprivation disrupts this process—bone formation markers drop while breakdown continues unchanged.
Poor sleep also disrupts growth hormone release and cortisol rhythms, both of which affect bone metabolism. Night shift workers face particular challenges due to circadian rhythm disruption.
The takeaway: Aim for 7-8 hours per night with consistent sleep and wake times. Address sleep disorders if you have them.
Stress and Bone Health
Chronic stress doesn't just affect your mind—it affects your skeleton.
The cortisol connection: When you're stressed, your body releases cortisol. Short-term, this is fine. But chronic stress means chronically elevated cortisol, and cortisol is hard on bones:
- Inhibits osteoblasts (building cells)
- Promotes osteoclast activity (breaking cells)
- Interferes with calcium absorption
This isn't theoretical—Cushing's syndrome (excessive cortisol) causes osteoporosis in up to 70% of cases.
Perspective matters: Chronically elevated cortisol from poor sleep or ongoing stress can negatively affect bone, but the magnitude is usually much smaller than with steroid medications. Your body tightly regulates endogenous cortisol through feedback mechanisms, so levels rarely reach those seen with exogenous corticosteroids. The major exception is Cushing's syndrome, where cortisol is pathologically high.
It's also worth noting that cortisol isn't "bad" by default—it plays essential roles in regulating blood sugar, blood pressure, immune responses, and helping us respond to stress. Problems arise mainly when cortisol is chronically elevated or its normal daily rhythm is disrupted.
Managing stress for bone health: Exercise works double duty—it reduces stress AND directly helps bones. Other proven approaches: adequate sleep, meditation, social connection, and setting boundaries. Avoid using alcohol to cope (also bad for bones).
Pregnancy, Breastfeeding, and Bones
Many women worry about bone loss during pregnancy and breastfeeding. Here's what you need to know.
Normal changes: The growing baby needs calcium, and some comes from maternal bones. During breastfeeding, bone loss of 4-6% in the first 6 months is typical—and this occurs regardless of calcium intake. The body prioritizes the baby's needs.
The good news: Bone density typically returns to normal after weaning—usually within 12 months. Long-term studies show no increased fracture risk from breastfeeding. Extra calcium won't prevent the temporary loss, and it doesn't need to. Recovery is part of the normal process.
When to be concerned: Pregnancy and Lactation-Associated Osteoporosis (PLO) is rare but serious—it can cause vertebral fractures during or after pregnancy. Risk factors include very low body weight, eating disorders, and multiple closely-spaced pregnancies. If you have unexplained back pain during pregnancy or nursing, get evaluated.
The Bottom Line
Sleep, stress, and reproductive events all affect your bones in ways many people don't realize.
- Sleep: 7-8 hours supports normal bone remodeling
- Stress: Chronic cortisol elevation damages bones; stress management is bone health
- Pregnancy/Breastfeeding: Temporary loss is normal; recovery happens after weaning
These factors are often overlooked—especially for people doing "everything right" who still have problems.