Homeostatic Regulation of Sleep in Short Sleepers

Overview

This single-center study targets adults with distinct sleep profiles, divided into three categories: natural short sleepers, characterized by a reduced nocturnal sleep duration; subjects with idiopathic hypersomnia (IH) followed at the Sleep Disorders Unit of CHU Gui de Chauliac, with excessive daytime sleepiness; and control normal sleepers, with standard sleep duration and no specific complaints. The aim of this study is to analyze the mechanisms of slow-wave regulation during sleep according to sleep phenotype (normal, short, and long sleepers/idiopathic hypersomnia) by examining the decay of EEG spectral power in the delta band over central regions during the first night of continuous 32-hour recording.

Detailed description

Sleep is a fundamental biological process essential for maintaining brain and systemic homeostasis, playing a key role in regulating cognitive, metabolic, and emotional functions. Over the past decades, numerous studies have shown that chronic sleep deprivation is associated with an increased risk of cardiovascular disease, diabetes, metabolic disorders, and cognitive deficits.

However, individuals differ in the amount of sleep they need for optimal functioning, suggesting inter-individual variability in homeostatic sleep regulation. Slow waves during sleep (0.5-4 Hz) are central to this regulation and closely reflect sleep pressure accumulated during wakefulness. During deep sleep, slow waves support the reorganization of neural connections, brain detoxification, and restoration of energy reserves. A reduction in slow-wave power, observed with aging or in pathological conditions, has been linked to reduced recovery capacity and increased cognitive vulnerability.

Sleep need is partly determined by genetics and varies between individuals. Approximately 5-7% of the population are short sleepers, able to maintain optimal cognitive and emotional performance despite sleeping ≤6 hours per night. Previous research suggests that short sleepers may compensate for shorter sleep by increasing sleep depth in the early phases, allowing faster recovery than hypersomnia patients.

At the other end of the spectrum is idiopathic hypersomnia (IH), a condition marked by excessive sleep need and persistent daytime sleepiness despite prolonged nocturnal sleep. Its pathophysiology remains poorly understood but may involve altered slow-wave regulation and impaired homeostatic sleep pressure.

The goal of this study is to compare slow-wave architecture among short sleepers, normal sleepers, and individuals with idiopathic hypersomnia to better understand inter-individual differences in sleep homeostasis. We hypothesize that delta power decay during the first night of recording will be faster and more pronounced in short sleepers, reflecting accelerated dissipation of sleep pressure, while it will be slower and less marked in IH patients, indicating impaired homeostatic regulation. This project will provide a detailed assessment of the neurophysiological mechanisms underlying differences in sleep profiles and their implications for health and cognitive functioning.

Interventions

• Procedure Actigraphy
  Actigraphy is a non-invasive method for measuring physical activity and sleep-wake cycles over an extended period, specifically two weeks in this protocol. It uses a small, portable device, the actigraph, which is often worn on the wrist of the non-dominant arm and continuously records the participant's movements. The data collected enables the estimation of periods of sleep and wakefulness, sleep quality, and circadian rhythms.
• Procedure Polysomnographie (PSG 128)
  A video-polysomnography recording will be carried out to enable the scoring of the different stages of sleep and the analysis of the following parameters: \- Electroencephalogram (EEG): A high-density cap (128 electrodes) will be fitted to record brain activity \- Electromyogram (EMG): Three leads will be recorded at the chin. \- Electrooculogram (EOG): Right and left eye movements will be recorded in phase opposition \- Additional sensors will be fitted to record: * Leg movements, using el
• Procedure TILE test
  The modified TILE consists of five nap opportunities scheduled at 9 a.m., 11 a.m., 1 p.m., 3 p.m., and 5 p.m., during which participants are awakened after one minute of sleep to preserve the homeostatic process. Participants then undergo a modified TILE test, during which they are awakened each time they fall asleep. This allows for the measurement of sleep latency, defined as the time taken to fall asleep and the detection of abnormal REM sleep episodes.
• Procedure PVT
  The PVT is a standardised computer-based test lasting 5 minutes, used to assess sustained attention and psychomotor reactivity. At random intervals, a visual stimulus in the form of a digital stopwatch appears on the screen. The participant must then react as quickly as possible by pressing a button as soon as the stimulus appears, in order to stop the stopwatch. The test provides objective measures such as reaction time, the number of response omissions (lapses) and false alarms, offering a rel
• Biological Blood sample
  The first blood sample will be collected during hospitalization to obtain serum for biobank establishment, and a second blood sample will be collected at the end of the protocol to obtain serum for biobank establishment.
• Procedure Freestyle Libre® senso
  The Abbott® FreeStyle Libre Pro iQ® is a continuous glucose monitoring system designed to measure interstitial glucose levels in real time in participants enrolled in clinical trials. This non-invasive, painless device is worn on the skin and continuously measures glucose concentrations in interstitial fluid, providing an accurate assessment of the glucose profile without the need for frequent blood sampling. The sensor will be fitted to provide continuous measurement of interstitial glucose lev
• Behavioral Questionnaires
  During their hospital stay, participants will complete a series of questionnaires designed to document sleepiness, daytime functioning, sleep quality, dietary and physical activity habits, and circadian rhythms: ESS, KSS, FOSQ, WPAI, IHSS, ISI, IPAQ, FFQ. Study of the chronobiological profile of participants, using the Morningness Eveningness Questionnaire (MEQ) by Horn and Östberg."
• Procedure Home EEG monitoring
  One week after hospitalization, sleep monitoring will be carried out at home using the Dreem® headband, a lightweight wearable EEG device designed to be worn during sleep. The headband features four electrodes positioned to measure brain activity in real time with high accuracy and connects wirelessly to a mobile application for easy data collection. It enables continuous recording of EEG signals, allowing identification of sleep stages as well as sleep microstructures such as spindles and slow
• Procedure Bioelectrical impedance analysis
  Will be conducted to evaluate body composition, including fat mass, lean mass, and total body water.

Primary outcome measures

• The decrease in EEG spectral power in the delta band (0.5-4 Hz) over the central region during the first night of a continuous 32-hour recording. [Time frame: Day 17]

Secondary outcome measures (12)

• Changes in EEG spectral activity [Time frame: Day 17]
• 24-hour glycemic variability [Time frame: Up to Day 18]
• Lean mass index [Time frame: Up to Day 18]
• Fat mass index [Time frame: Up to Day 18]
• Physical activity level assessed using the International Physical Activity Questionnaire IPAQ [Time frame: Baseline visit (V1)]
• Food Frequency Questionnaire score [Time frame: Baseline visit (V1)]
• Epworth Sleepiness Scale (ESS) score [Time frame: Baseline visit (V1)]
• Idiopathic hypersomnia severity scale (IHSS) score [Time frame: Baseline visit (V1)]
• Karolinska Sleepiness Scale (KSS) [Time frame: Baseline visit (V1)]
• The number of sleep-onset REM periods (SOREMPs) [Time frame: Up to Day 18 (During hospitalization)]
• Sleep latency at each test (minutes) [Time frame: Up to Day 18 (During hospitalization)]
• Mean sleep latency is the average time (in minutes) [Time frame: Up to Day 18 (During hospitalization)]

Eligibility criteria

Inclusion criteria

• Be aged ≥ 18 years
• Be affiliated with a social security system
• Be able to understand the nature, purpose, and methodology of the study and agree to cooperate during clinical and polysomnographic assessments
• Be fluent in French (speaking and writing)
• Have provided written informed consent
• Sleep duration:
• Short sleepers:

Weekday sleep duration ≤ 6 hours, with no significant increase at the weekend (weekend sleep duration ≤ 7 hours) and no complaints of daytime sleepiness (ESS <10).

-Normal sleepers: Weekday sleep duration of between 7 and 8 hours, with weekend sleep duration generally similar or slightly longer (between 7 and 9 hours), reflecting a normal sleep duration without restriction or significant catch-up sleep, and with no complaints of daytime sleepiness (ESS <10).

-HI subjects, with increased sleep duration: Increased sleep need, with a reported sleep duration of ≥ 10 hours per night and > 11 hours over a 24-hour period; increased sleep duration associated with excessive daytime sleepiness not explained by another sleep disorder.

• No other sleep disorders
• Apnoea-hypopnoea index (AHI) ≤ 15/h
• Periodic limb movement index ≤ 15/h

Exclusion criteria

• Pre-existing sleep disorders
• Use of medication that affects sleep (such as sedatives, antidepressants, and insomnia medication);
• Use of substances that disrupt sleep or reduce fatigue
• Serious psychiatric disorders
• Pregnancy or breastfeeding
• Persons deprived of their liberty (by court order or administrative decision)

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Non-randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Diagnostic

Study locations

France · 1 center

• Gui de Chauliac - CHU Montpellier — Montpellier

Identifiers

NCT: NCT07584538 · RECHMPL25_0538

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗