Neurophysiological and Sleep-Related Effects of a Cosmetic Shampoo and Conditioner in Adults With Scalp Discomfort

Neurophysiological, Sleep-Related, and Mood Effects of a Cosmetic Shampoo and Conditioner Regimen in Adults With Scalp Discomfort and Sleep Difficulty: A Pilot EEG-Based Observational Study

The goal of this clinical trial is to learn whether regular use of Nizoral® Daily Prevent shampoo and conditioner can improve scalp comfort, sleep experiences, mood, and overall well-being in adults who have scalp discomfort and difficulty sleeping. The main questions it aims to answer are:

1. Does using the shampoo and conditioner improve scalp comfort and reduce the impact of scalp discomfort on daily life?
2. Does using the shampoo and conditioner improve sleep experiences and how rested participants feel?
3. Does using the shampoo and conditioner affect mood and other measures of well-being?.

Participants completed a one-week period without hair products, followed by two weeks of using the study shampoo and conditioner at least three times per week. During the study, participants:

1. Attended weekly study visits.
2. Answered questions about their scalp comfort, sleep, and daily experiences.
3. Wore a wrist-based sleep tracking device throughout the study. Completed weekly questionnaires about sleep and scalp health.
4. Took part in non-invasive brain activity measurements during study visits.

Study Overview

• Status: Completed
• Conditions: Dandruff
• Intervention / Treatment: Other: Cosmetic Shampoo and Conditioner Regimen

Detailed Description

This was a prospective, single-arm, observational study evaluating the effects of regular use of a cosmetic shampoo and conditioner on scalp comfort, sleep-related experiences, mood, and neurophysiological responses in adults reporting scalp discomfort and sleep difficulties.

Participants were recruited from an internal volunteer database and screened against predefined eligibility criteria. All participants provided written informed consent before any study procedures.

The study consisted of four weekly visits: a baseline visit (EEG, scalp and sleep questionnaires, initiation of Fitbit sleep monitoring), a washout visit one week later with no hair products, followed by two further visits assessing early and extended effects after approximately one and two weeks of product use, respectively. Daily sleep monitoring and weekly questionnaires continued throughout.

EEG recordings were analyzed using Cognalyzer® EEG-based metrics, including mood valence, relaxation, sleepiness, anger, and mental arousal. The primary objective was to evaluate changes in neurophysiological and self-reported measures of scalp comfort, sleep experiences, mood, and well-being following product use; exploratory objectives included sleep-related outcomes and EEG-derived indicators of emotional and cognitive state.

• Study Type: Observational
• Enrollment (Actual): 21

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Hamilton, Ontario, Canada, L8P 1J4
      • Zentrela Inc.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Participants were recruited from an existing volunteer database maintained by the research site in Hamilton, Ontario, Canada. The study population consisted of community-dwelling adults interested in participating in consumer product research. Recruitment was conducted through database outreach and screening questionnaires. Participants were selected from the local community and represented a range of ages and both sexes.

Description

Inclusion Criteria:

1. Age 18 years or older.
2. Reported at least one scalp symptom within the past 2 weeks, such as itching, dryness, sensitivity, redness, or flakes.
3. Experienced scalp discomfort occasionally or more often during the past 2 weeks.
4. Reported a scalp discomfort rating of 4 or higher on a 0-10 scale.
5. Reported difficulty falling asleep or staying asleep within the past 2 weeks.
6. Experienced sleep difficulty more than once per week.
7. Willing and able to use the study shampoo and conditioner at least 3 times per week during the study.
8. Willing and able to wear a Fitbit sleep-tracking device during the study.
9. Able to attend all scheduled study visits.
10. Able to provide informed consent.

Exclusion Criteria:

1. Current use of medicated scalp treatments or use within the previous 14 days.
2. Known allergy or sensitivity to ingredients commonly found in shampoos or conditioners.
3. Ongoing scalp conditions, including active psoriasis, eczema, or open sores.
4. Use of sleep aids, sedatives, antihistamines, or other medications that affect sleep more than once per week during the previous 2 weeks.
5. Participation in another clinical, cosmetic, or consumer research study within the previous 30 days.
6. Any condition that, in the opinion of the investigators, could interfere with study participation, compliance with study procedures, or interpretation of study results.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Dandruff Group	Other: Cosmetic Shampoo and Conditioner Regimen; Participants used the study cosmetic shampoo together with the study cosmetic conditioner at least three times per week for two consecutive weeks, following a one-week washout period without hair products.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in EEG-Derived Mood Valence	EEG-derived mood valence, reflecting positive versus negative emotional state, compared between baseline visits (1-2) and product-use visits (3-4).	Up to 4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in EEG-Derived Relaxation Level	EEG-derived relaxation level compared between baseline and product-use visits.	Up to 4 weeks
Change in EEG-Derived Sleepiness Level	EEG-derived sleepiness indicators compared between baseline and product-use visits.	Up to 4 weeks
Change in EEG-Derived Anger Level	EEG-derived anger-related response compared between baseline and product-use visits.	Up to 4 weeks
Change in Self-Reported Scalp Comfort	Weekly questionnaire measures of scalp itch and discomfort compared between baseline and product-use periods.	Up to 4 weeks
Change in Self-Reported Sleep Quality	Weekly questionnaire measures of sleep onset, night-time waking, and feeling rested, compared between baseline and product-use periods.	Up to 4 weeks
Change in Fitbit-Measured Sleep Parameters	Wearable-derived sleep metrics collected nightly, compared between baseline and product-use periods.	Up to 4 weeks

Collaborators and Investigators

• Sponsor: Zentrela Inc.
• Collaborators: Thornton & Ross
• Investigators: Principal Investigator: Dan Bosnyak, PhD, McMaster University

Publications and helpful links

General Publications

• Bosnyak D, McDonald AC, Gasperin Haaz I, Qi W, Crowley DC, Guthrie N, Evans M. Use of a Novel EEG-Based Objective Test, the Cognalyzer(R), in Quantifying the Strength and Determining the Action Time of Cannabis Psychoactive Effects and Factors that May Influence Them Within an Observational Study Framework. Neurol Ther. 2022 Mar;11(1):51-72. doi: 10.1007/s40120-021-00293-w. Epub 2021 Nov 2.
• McDonald AC, Gasperin Haaz I, Qi W, Crowley DC, Guthrie N, Evans M, Bosnyak D. Sensitivity, Specificity and Accuracy of a Novel EEG-Based Objective Test, the Cognalyzer(R), in Detecting Cannabis Psychoactive Effects. Adv Ther. 2021 May;38(5):2513-2531. doi: 10.1007/s12325-021-01718-6. Epub 2021 Apr 7.

Study record dates

Study Major Dates

• Study Start (Actual): November 7, 2025
• Primary Completion (Actual): February 7, 2026
• Study Completion (Actual): February 7, 2026

Study Registration Dates

• First Submitted: June 25, 2026
• First Submitted That Met QC Criteria: June 25, 2026
• First Posted (Actual): July 2, 2026

Study Record Updates

• Last Update Posted (Actual): July 2, 2026
• Last Update Submitted That Met QC Criteria: June 25, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: dandruff, EEG, well-being
• Additional Relevant MeSH Terms: Skin Diseases; Dermatitis; Scalp Dermatoses; Skin and Connective Tissue Diseases; Dandruff
• Other Study ID Numbers: CUSIC-74

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data collected during this study, including electroencephalography (EEG), questionnaire, and wearable device data, will not be made available to other researchers. The study was conducted as a sponsor-supported consumer product research study, and there is no plan to share de-identified participant-level datasets or supporting data dictionaries outside the study team.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No