What poor sleep does to your hormones and blood sugar

Poor sleep changes your hormones and your blood sugar faster than you think. After just a week of short nights your testosterone drops, your evening cortisol rises and your insulin sensitivity worsens. Sleep is therefore one of the most powerful, and most underrated, levers for your blood values.

I think sleep is the cheapest performance enhancer there is. And the first thing people sacrifice.

Does sleep loss lower your testosterone?

A week of too little sleep can measurably lower testosterone in healthy young men. In a controlled study, testosterone fell by about 10 to 15% during the day after five hours of sleep per night for a week (Leproult, 2011). That is a difference you would normally only see after years of ageing.

So you best measure your testosterone after a period of normal sleep, not after a bad week.

What does sleep loss do to cortisol and blood sugar?

Sleep loss shifts your stress hormone and your sugar handling the wrong way. After a few nights of short sleep, your evening cortisol rises and your glucose tolerance worsens (Spiegel, 1999). A week of five hours of sleep lowered insulin sensitivity by about 20% (Buxton, 2010).

Why the timing of your blood test matters

Because sleep affects your values so strongly, a bad week skews your result. Test your testosterone, cortisol and sugar values after a few normal nights, not after a deadline week or short nights. Otherwise you measure your sleep loss, not your baseline.

For the sugar side, read fasting insulin and HOMA-IR.

How to use this

Treat sleep as part of your training and recovery plan, not an afterthought. To track the effect of your sleep on your hormones, measure in a calm, well-slept period and repeat later. Compose your panel through our custom blood test.

Also read alcohol and your blood values and fasted cardio.

My advice: fix your sleep before you reach for supplements or a testosterone course. If your symptoms persist despite good nights, discuss it with your GP.

References

1. Leproult R, Van Cauter E. Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA. 2011. PMID: 21632481.
2. Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. The Lancet. 1999. PMID: 10543671.
3. Buxton OM, Pavlova M, Reid EW, et al. Sleep restriction for 1 week reduces insulin sensitivity in healthy men. Diabetes. 2010. PMID: 20585000.

Disclaimer

Every blood test result includes a professional assessment by a BIG-registered doctor. This article gives general information and is not a substitute for medical advice. A blood test is a tool to walk into the conversation with your GP better informed, not a diagnosis in itself. For treatment decisions, discuss your results with your GP.