Wellness Lab

Sleep Health Library

Sleep Health

Updated January 11, 2026
About the Sleep Lab
nutreska wellness lab · sleep health

This library organizes evidence-informed answers to frequently asked questions and explanations of how sleep works. For references or further reading, contact us and we can provide publication details from the National Library of Medicine.

contributors
Dr. Richard Schanz — Head of Product at Nutreska

Dr. Richard
Schanz
Head of Research
Nutreska Labs
Dr. James Redfern — Senior Researcher at Nutreska Labs

Dr. James
Redfern
Head of Product
Nutreska Clinical
Dr. Melanie Parker — Junior Researcher at Nutreska Labs

Dr. Melanie
Parker
Senior Research
Nutreska Labs
Dr. Charles M. Morin — Contributor (Guest)

Dr. Charles M.
Morin
Guest Contributor
CERVO
Sleep quality Circadian rhythm Melatonin timing REM sleep Deep sleep Stress & cortisol Habits & substances Hormones & metabolism Aging & sleep needs
Browse by domain
Quality Timing Sleep Stages Mental Health Body & Metabolism Habits Aging
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Why do I wake up tired even after 8 hours of sleep?

A high-yield overview of sleep quality vs sleep timing — and what typically explains unrefreshing sleep.

Sleep Quality

Questions about why sleep doesn’t feel refreshing or restorative.
Why do I wake up tired even after 8 hours? What makes sleep feel restorative? Why is my mind tired but my body can’t sleep? Why do I wake up at 3AM every night?

Timing & Rhythm

Questions about when sleep happens and why it feels mistimed.
What is the best time to take melatonin? Is it better to go to bed early or wake up early? Does sleeping in on weekends hurt sleep? What is sleep debt?

Sleep Stages

Questions about what happens during sleep and what may be missing.
What is REM sleep and why does it matter? What is deep sleep and how can I get more? What happens to your brain without sleep?

Mental Health

Questions about how stress, anxiety, and sleep influence each other.
Why does stress make it hard to sleep? Why do I feel anxious after poor sleep?

Body & Metabolism

Questions about how sleep affects hormones, weight, pain, and physiology.
How does sleep affect hormones? Can poor sleep cause weight gain? Why does poor sleep increase pain? Can gut health affect sleep?

Habits & Substances

Questions about behaviors and substances that may interfere with sleep quality.
Is it bad to use your phone before bed? Does alcohol really help sleep? Does magnesium actually help sleep? Can naps ruin sleep? Why do naps make me groggy?

Aging & Needs

Questions about how sleep changes across different stages of life.
How many hours of sleep do adults need? Is melatonin safe to take every night? Why is sleep harder as you age?
Nutreska Wellness Lab knowledge base. Frequently updated to accurately reflect new discoveries and research.
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Have a Question or Concern?

Get evidence-based advice from doctors and research biologists. Use the form to submit a query.

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Note: Medical advice requires an on-site diagnosis. If symptoms are severe, please schedule an appointment to see a clinician.

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Note: We can’t provide medical advice or diagnose conditions. If symptoms are severe or persistent, consider speaking with a clinician.