24/03/2026
🌙 Sleep is often treated as optional.
The evidence suggests it is one of the most important biological processes for maintaining metabolic, cardiovascular, immune and brain health.
Here are seven findings from sleep science showing what chronic sleep restriction may do to the body.
1. Two weeks of sleeping about six hours per night produced cognitive impairment similar to staying awake for 24 hours. Participants also underestimated how impaired they had become.
2. Sleeping fewer than six hours per night is associated with roughly a 20 to 48 percent higher risk of cardiovascular disease compared with seven to eight hours of sleep.
3. Restricting sleep to about five hours per night for one week reduced insulin sensitivity by about 20 to 25 percent, pushing the body toward a pre diabetic metabolic state.
4. People sleeping fewer than six hours per night were more than four times as likely to develop a cold when exposed to a virus.
5. Sleep restriction increases ghrelin, the hormone that stimulates hunger, by about 24 percent. This shift may increase appetite and cravings for calorie dense foods.
6. Large meta analyses show habitual short sleep is associated with roughly a 12 percent higher risk of premature death.
7. During deep sleep the brain activates the glymphatic system, helping clear metabolic waste including beta amyloid, a protein associated with Alzheimer’s disease.
Sleep is not passive rest. It is biological maintenance.
Sleep sits at the top of the health hierarchy for my patients. Improve sleep and you improve your life.
Sweet Dreams, Dr Z x
References
Van Dongen 2003 Sleep
Cappuccio 2011 European Heart Journal
Buxton 2010 Science Translational Medicine
Prather 2015 Sleep
Spiegel 2004 Annals of Internal Medicine
Cappuccio 2010 Sleep
Xie 2013 Science
