Chronic sleep deprivation: how harmful is it for weight and hormones?
Chronic sleep deprivation disrupts your hormones and metabolism after just a few nights. Structurally sleeping too little increases the risk of weight gain, muscle loss and diabetes.
After just six nights of four hours of sleep, your carbohydrate metabolism starts to go haywire. In a controlled experiment with eleven young men, blood sugar regulation deteriorated considerably, and the researchers observed effects resembling normal ageing. At the same time, the hormone that controls your thyroid (TSH) dropped. Less than one week of insufficient sleep was enough.
Your stress hormone cortisol is supposed to be low in the evening. After six nights of four hours, evening cortisol was strongly elevated (p=0.0001). Even one completely sleepless night raised cortisol by 21%. That same sleepless night lowered testosterone by 24%. More of a breakdown hormone and less of a building hormone at the same time: that is a double blow to your recovery.
Your muscles notice it directly too. One night of total sleep deprivation reduced muscle protein synthesis in thirteen healthy young adults by 18% (p=0.040). Sleep deprivation also increases your appetite and total food intake, which over time worsens your body composition.
With chronically disrupted sleep, such as in sleep apnoea, your insulin sensitivity also deteriorates. Sleep apnoea and excess weight reinforce each other in a vicious cycle. In addition, elevated cortisol drives your preference for calorie-dense and high-fat foods through reward circuits in the brain. This mechanism extends beyond sleep deprivation alone, but the overlap is biologically plausible.
Large population studies show that short sleep is associated with a higher risk of obesity, type 2 diabetes, high blood pressure and heart disease. These are not hard cause-and-effect proofs, but they fit precisely with the mechanisms found in the controlled experiments.
The controlled findings come from small experiments (11-13 participants, one study per outcome), but the effects are consistent and statistically significant. The associations from population studies have been corrected for various factors, but remain associative. Together, the studies paint a consistent picture of multiple independent harmful mechanisms.
Are sleeping pills harmful in the long term?
Long-term use of classic sleeping pills increases the risk of dependence, cognitive decline, and impaired driving ability. Therefore, do not use them for longer than two to four weeks, and discuss alternatives with your doctor if you are already a long-term user.
How harmful is irregular sleep or shift work, and what can you do about it?
Shift work is demonstrably harmful to sleep, alertness and metabolism. The best approach combines a well-designed schedule with forward rotation, strategic use of light, melatonin and, where appropriate, cognitive behavioural therapy.
Why do you sleep worse as you get older, and do hormones play a role in that?
Sleeping worse with age is well documented and has multiple causes, including brain changes and, in women, the menopause. Hormones play a role, but often indirectly, such as through hot flushes, so hormone therapy is not a straightforward answer for everyone.
Does poor sleep really shorten your life?
Consistently sleeping too little is associated with a measurably higher risk of earlier death and serious illness; the evidence is strongly associative, so aiming for seven to eight hours of sleep per night is sensible, especially if you also get little exercise.
What does alcohol do to the quality of my sleep, and is there anything that can be done about it?
Alcohol helps you fall asleep faster, but measurably disrupts the rest of your night, even with just two drinks. If you want to sleep better, drinking less or no alcohol before bed is the most effective step.
Can sleep deprivation raise your blood pressure?
Chronically sleeping too little is associated with a clearly elevated risk of high blood pressure. If your blood pressure is raised and you are structurally sleeping too little, that is a good topic to discuss with your doctor.