Frequently Asked Questions

How much sleep do people really need?

Most adults need 7–9 hours of sleep per night for optimal physical, mental, and cognitive health. However, over two-thirds of United States Military Service Members report sleeping 6 hours or less, which can affect performance, recovery, and long-term health.

Are commercial sleep wearables reliable?

Wearables—like smartwatches and rings—offer convenient estimates of sleep duration and heart rate, but their accuracy varies when it comes to tracking specific sleep stages such as REM or deep sleep. In some individuals, excessive reliance on sleep data from these devices may contribute to orthosomnia—a form of sleep disturbance driven by anxiety over sleep tracking. Research from the Department of Defense and affiliated institutions has evaluated the reliability of wearables, finding certain metrics to be reasonably accurate while others fall short. Our lab contributes to this effort by comparing consumer-grade wearables with clinical tools to assess their utility for field-ready sleep monitoring in operational settings.

To learn more about the reliability of commercial sleep wearables and strategies for better sleep:

• WRAIR’s Sleep Resources page

• The VA’s Path to Better Sleep program

• Dr. Evan Chinoy’s study on wearable accuracy and sleep staging

• NHRC’s Role in RIMPAC’s Military Health Experimentation Sector

How does blast exposure affect sleep?

Repeated low-level blast exposure—like that experienced during breacher training—can disrupt brain function and sleep patterns. These disruptions may affect deep sleep quality, circadian rhythms, and increase the risk of long-term issues like insomnia, mood changes, or fatigue.

What is the glymphatic system, and why does it matter?

The glymphatic system is your brain’s waste clearance pathway. It’s most active during deep sleep, when it clears toxins and metabolic waste from brain tissue. Disruptions in sleep, especially REM and slow wave sleep, may impair this system—contributing to memory problems and increased risk for neurodegenerative diseases like Alzheimer’s.

• First reported characterization of the glymphatic system

• Beginner’s guide to glymphatics

• Review paper on glymphatic dysfunction as a path to neurodegeneration via sleep disruption

• Poor sleep quality may alter glymphatic function

• Seminal paper on MRI assessed glymphatic clearance in healthy controls vs. dementia patients

• Sleep deprivation disrupts metabolic waste clearance from the human brain (glymphatic disruption)

• Sleep deprivation impairs molecular clearance from human brain video abstract (must watch!)

Have more questions?

Check out our Lab’s Background or submit a contact form inquiry.