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Research & studies

The science behind better nights.

WakeZ grew out of sleep research and it still runs on it. This is how we estimate sleep from a watch, how we check those estimates against the lab, and what our team has published about sleep and depression. This page describes research. None of it is a feature of the WakeZ app.

Read our papersBrowse all studies

One night, two measurements

Participant 0213 · Night 14 · illustrative data

WakeZ estimatePolysomnography (lab reference)
AwakeREMLightDeep
23:0001:0003:0005:0007:00

Compared in 30-second epochs

Evidence at a glance

A growing body of evidence

Every feature in WakeZ started as a research question. Here is where the work stands today.

Peer-reviewed papers
4
Published 2023 to 2025
Largest study
191
Adults, 15 nights, Apple Watch
Nights in our sleep lab
300+
Recorded with polysomnography and Apple Watch together
Participants
208
In our randomised trial

The critical role of REM sleep

Where sleep and depression meet

The relationship between REM sleep and depression is where our research began.

REM sleep and depression

Studies have consistently shown that depression is linked with distinct changes in REM sleep, such as earlier onset, increased density and prolonged duration[1][2]. These changes matter because serotonin and noradrenaline, key neurotransmitters in managing depression, cease their activity during REM sleep.

Antidepressants and REM pressure

Antidepressants often exert their therapeutic effect by applying “REM pressure”, altering the architecture of REM sleep. This is considered one of the primary mechanisms through which these medications work.

Further readingOxford Scientist · June 2023

The troubled relationship between REM sleep and depression

The University of Oxford’s science magazine on the link between REM sleep and depression, and why understanding it matters for treating depression.

Read the article

References

  1. [1]Baglioni C, Nanovska S, Regen W, Spiegelhalder K, Feige B, Nissen C, Reynolds CF, Riemann D. Sleep and mental disorders: A meta-analysis of polysomnographic research. Psychol Bull. 2016;142(9):969–990. DOI
  2. [2]Riemann D, Berger M, Voderholzer U. Sleep and depression — results from psychobiological studies: an overview. Biol Psychol. 2001;57(1–3):67–103. DOI

Wake therapy, a history

An idea psychiatry has explored for fifty years

  1. 1970s

    Wake therapy

    Since the 1970s, psychiatrists have experimented with REM sleep deprivation as a potential treatment for depression. Known as wake therapy, or sleep deprivation therapy, it has shown efficacy comparable to antidepressants in some studies.

  2. Now

    Research into REM sleep

    Our team is testing, in a randomized trial, whether fine vibrations during REM sleep can reduce depressive symptoms. The paper is in peer review. This is research, and it is not part of the app.

Featured study

REM sleep and depressive symptoms, measured with a watch

Our largest published study asked a simple question: does the REM sleep an Apple Watch records say anything about how depressed a person feels?

Peer-reviewedDiagnostics, 2025

Assessing REM Sleep as a Biomarker for Depression Using Consumer Wearables

191 adults wore an Apple Watch for 15 nights and completed a standard depression questionnaire.

Key finding

REM latency and REM proportion were related to the severity of depressive symptoms. The model explained 62% of the variation in symptom severity.

Design
Observational
Participants
191 adults
Duration
15 nights
Setting
At home, with an Apple Watch

This is research by our team. The WakeZ app does not use REM to assess anyone. It shows you your sleep and, if you choose, sends it to a doctor.

Read the paper

REM latency and symptom severity

191 participants · illustrative chart

Symptom severity

REM latency

The library

All studies & papers

Peer-reviewed research by the WakeZ team, and the trial now under review.

Showing 5 of 5

  • Peer-reviewed2025

    Assessing REM Sleep as a Biomarker for Depression Using Consumer Wearables

    REM latency and REM proportion related to depressive symptom severity; the model explained 62% of the variation.

    • 191 participants
    • 15 nights
    • Diagnostics
    Read the paper: Assessing REM Sleep as a Biomarker for Depression Using Consumer Wearables
  • Peer-reviewed2024

    Deciphering the Link: Correlating REM Sleep Patterns with Depressive Symptoms via Consumer Wearable Technology

    REM patterns recorded by the watch correlated with depressive symptoms (rho = 0.70).

    • 105 participants
    • about 30 nights
    • Journal of Personalized Medicine
    Read the paper: Deciphering the Link: Correlating REM Sleep Patterns with Depressive Symptoms via Consumer Wearable Technology
  • Peer-reviewed2024

    A new dawn: The next frontier in AI-driven sleep enhancement through gradual awakening

    Waking up, sleep quality and quality of life improved on validated scales. One group, self-reported, earlier version of the alarm.

    • 100 participants
    • 30 nights
    • World Journal of Advanced Engineering Technology and Sciences
    Read the paper: A new dawn: The next frontier in AI-driven sleep enhancement through gradual awakening
  • Peer-reviewed2023

    A Narrative Review on REM Sleep Deprivation: A Promising Non-Pharmaceutical Alternative for Treating Endogenous Depression

    A review of what is known about REM sleep deprivation. The starting point of our research.

    • Journal of Personalized Medicine
    Read the paper: A Narrative Review on REM Sleep Deprivation: A Promising Non-Pharmaceutical Alternative for Treating Endogenous Depression
  • In peer review2026

    Randomized trial on fine vibrations during REM sleep (title to follow on publication)

    208 people, four weeks, in their own beds. Results will be published here the day the paper is out.

    • 208 participants
    • 4 weeks
    Under review

How we measure

From the wrist to the evidence

Every number in WakeZ travels the same path, from a watch on the wrist to results we can stand behind.

  1. Step 1

    Wearable signals

    Heart rate and movement are recorded overnight by the Apple Watch, and sleep is read from Apple Health. Nothing for the wearer to do.

    Apple Watch and iPhone

  2. Step 2

    Sleep estimation

    Our models tell asleep from awake, and they are trained on 2,917 nights from 164 people.

    30-second epochs

  3. Step 3

    Checked against the lab

    About 300 nights were recorded with polysomnography and an Apple Watch on the same sleeper at the same time, in our sleep laboratory in Cluj-Napoca.

    Polysomnography, the lab reference

  4. Step 4

    Followed after release

    WakeZ is a medical device, so we keep following it once people use it. Every report of a missed alarm is investigated, and we review the published science on sleep at least once a year.

    As medical device rules require

Every estimate is published with its limits: what it gets right, and where it still falls short.

Research collaboration

Let’s study better nights, together.

We partner with clinics, research groups and sleep labs on new studies. If you work on sleep and mental health, we’d like to hear from you.

  • Protocol design support
  • Anonymised data access
  • Devices for participants
  • Co-authored publications
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WakeZ is a Class I medical device, CE marked. It supports sleep awareness, a consistent sleep routine and self-reflection, as a measure intended to help reduce the risk of depression in adults aged 18 to 65 who are at risk and not diagnosed. It does not diagnose or treat any condition and is not an emergency service.

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