Sleep After 50: What 6.5 Hours a Night May Be Costing You

Sleep After 50: What 6.5 Hours a Night May Be Costing You

Byfunctionover50@gmail.com

Six hours and 28 minutes.

That was my average night’s sleep in July, according to my Apple Watch. And honestly, I thought it was pretty good.

I was training almost every day, working toward an average of 45 minutes of exercise. I had cleaned up my diet, cut out casual sugar, quit drinking a few years ago, and tested 129 biomarkers to see what was actually happening inside my body.

But 17 markers were still outside the optimal range—including fasting glucose at 105 mg/dL, HbA1c at 5.7%, and triglycerides at 277 mg/dL.

So I kept asking the same question: What am I missing?

Sleep was the input I had never seriously tried to fix.

I’m not claiming that averaging 6 hours and 28 minutes caused my bloodwork. I don’t know that. That is why I’m treating this as an experiment: change the inputs, measure the outputs, and show the results.

Is 6.5 Hours of Sleep Enough After 50?

The Centers for Disease Control and Prevention recommends seven or more hours for adults ages 18–60, seven to nine hours for adults 61–64, and seven to eight hours for adults 65 and older.

That does not mean 6.5 hours is a medical emergency. Large observational studies often show a U-shaped relationship between sleep duration and mortality: both unusually short and unusually long sleep are associated with higher risk, with the lowest-risk range generally near seven to nine hours.

At six and a half hours, the mortality curve does not suddenly fall off a cliff. I’m not going to tell you that being 32 minutes short is killing you, because the evidence does not support that kind of certainty.

What caught my attention was what controlled sleep-restriction studies found in the blood—sometimes within days.

What Short Sleep Can Change

Sleep affects far more than whether you feel tired the next morning. The CDC connects adequate sleep with heart health and notes that chronic insufficient sleep is associated with conditions including high blood pressure, heart disease, stroke, obesity, and type 2 diabetes. Its practical guidance includes keeping a regular schedule and avoiding food, alcohol, and artificial light close to bedtime. See the CDC’s sleep and heart-health guidance.

Blood Sugar and Insulin Sensitivity

In controlled studies, restricting sleep has reduced insulin sensitivity—the body’s ability to respond effectively to insulin.

One NIH-indexed trial put 20 healthy men on five hours in bed per night for one week. Their insulin sensitivity fell compared with the sleep-replete condition. A separate randomized crossover study of moderate sleep restriction in healthy young adults also found signs of decreased insulin sensitivity after only three nights.

The National Institute of Diabetes and Digestive and Kidney Diseases summarizes a broader body of evidence linking insufficient or fragmented sleep with abnormal glucose metabolism and increased diabetes risk. You can read its review of sleep, circadian disruption, and glucose metabolism.

That does not prove my sleep caused my fasting glucose of 105 or my HbA1c of 5.7. But sleep is connected in the research to the exact neighborhood of biomarkers I am trying to move.

Testosterone

One small laboratory study restricted ten healthy young men to five hours of sleep per night for one week. Their daytime testosterone levels fell by roughly 10% to 15%.

Here is the important context: the participants averaged about 24 years old, and the experiment was far more severe than my 6.5-hour average. The finding is interesting, but it cannot simply be applied to every man over 50. The NIH-hosted study itself says further investigation is needed.

That distinction matters. Research can give us a reason to investigate without giving us permission to pretend we already know the answer.

Sleep Regularity May Matter as Much as Duration

The finding that changed how I think about sleep was not about total hours. It was about consistency.

A large prospective study used more than 10 million hours of accelerometer data from over 60,000 UK Biobank participants. More regular sleep was associated with lower all-cause mortality risk, and sleep regularity was a stronger predictor of mortality risk than sleep duration in the study’s models.

You can read the full NIH-hosted study on sleep regularity and mortality.

This was an observational study, so it shows association—not proof that a regular bedtime directly causes a longer life. But it reframed the problem for me.

During this experiment, I had a bad week. Life happened, my schedule broke, and my numbers drifted toward my old baseline. The old me would have called the whole experiment a failure.

But if regularity matters, one rough week is not the result. It is one battle.

The war is the average. What matters is what your body experiences over months, not what happened on one Tuesday.

The Four Changes I’m Testing

I started this protocol on July 28. Two changes are supplements; two are simple rules. This is my experiment—not a prescription for you.

1. Magnesium Glycinate With Vitamin D3 and K2

At about 8:00 p.m., I take a softgel containing magnesium glycinate, vitamin D3, and K2.

I’m testing magnesium for sleep, but the evidence is modest. Small trials—some in older adults with sleep problems—suggest a possible benefit, but the results are not conclusive. The NIH Office of Dietary Supplements notes that observational research has suggested a role for magnesium in sleep, while clinical trials have not consistently confirmed it.

The vitamin D is doing a different job. My vitamin D result was 19 ng/mL, one of the 17 flagged markers I am working to improve. The NIH vitamin D fact sheet explains what vitamin D does, recommended intakes, and the risks of taking too much.

You may have heard that vitamin D must be taken in the morning because nighttime dosing disrupts sleep. The evidence for that claim is thin. I’m sharing the uncertainty so you can discuss timing and dosage with your doctor.

2. Ashwagandha

I’m also taking 1,000 mg of ashwagandha at about 8:00 p.m. Some short-term studies suggest that certain preparations may help with insomnia or stress, but many trials are small, use different products, and sometimes receive industry funding.

The NIH National Center for Complementary and Integrative Health says some preparations may help with insomnia and stress, but long-term safety is not established. It also notes rare cases linking ashwagandha products with liver injury and warns about possible medication interactions and risks for people with certain medical conditions.

That is why this is something to discuss with a clinician—not something to add casually because an influencer mentioned it. I ran it past my doctor, and my quarterly blood panel includes liver enzymes so I can watch what happens.

3. Nothing to Eat or Drink After 8:00 p.m.

My third change is a rule: no food or drinks after 8:00 p.m.

This has a direct connection to the biomarkers I am watching. In a randomized crossover trial, eating dinner at 10:00 p.m. rather than 6:00 p.m. produced higher overnight glucose and reduced fat oxidation in healthy volunteers. The NIH-indexed late-dinner study was small and short-term, so it does not settle every question about meal timing. But it gives me a reasonable experiment to run.

If I am going to give my body seven or eight hours to recover, I would rather not spend the first part of that window digesting a late meal.

4. Screens Off at 9:45 p.m.

At 9:45 every night, the television goes off and the phone goes away.

You have probably heard that this is all about blue light. The blue-light research is more mixed than many headlines suggest. For me, that is not the main point.

The hard cutoff creates a consistent bedtime. It turns “I should go to bed soon” into an actual rule. And regularity is the sleep finding with the strongest legs in this experiment.

The rule matters more than the mechanism.

Is the Sleep Experiment Working?

It is early, but the direction is encouraging.

  • July baseline: 6 hours, 28 minutes per night
  • August average at the time of filming: 6 hours, 38 minutes
  • Best recent week: 6 hours, 54 minutes

That is progress, but more minutes of sleep are not the finish line. Sleep is the input.

The outputs are fasting glucose, HbA1c, triglycerides, hormones, recovery markers, and the rest of my 129-biomarker panel. I will repeat the panel in October, and whatever the results show—better, worse, or unchanged—I will share them.

That retest is the scoreboard.

The Question Every Man Over 50 Should Ask

If you are training, cleaning up your diet, and still wondering why certain health markers are not moving, ask yourself this:

Do you know how much you actually sleep?

Not how much time you spend in bed. Not what you think you get. Your measured average.

I would have guessed wrong by about half an hour. That half hour may or may not explain my bloodwork—but it was enough to reveal an input I had been ignoring.

Measure first. Change one or two things you can sustain. Watch the trend. Then retest the outcomes that matter.

You can follow every number on my live Function Over 50 scorecard.

And if you want to understand which blood markers to watch—including glucose, HbA1c, triglycerides, and what “normal” versus “optimal” means—download the free Biomarker Decoder.

I’m not a doctor, dietitian, or trainer. I’m a 50-year-old man measuring my own health and showing my work. This article describes my personal experiment and is not medical advice. Talk with your physician before starting a supplement or changing your diet, particularly if you take medications or have a medical condition.

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