NASA PVT+ vs Optimal HRV
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
NASA PVT+
This app provides a validated tool for conducting psychomotor vigilance tests, crucial for sleep, alertness, and performance research. It offers multiple study frameworks, including simple tests, basic multi-day studies, and specialized aviation research protocols.
- Psychomotor Vigilance Test (PVT)
- Karolinska Sleepiness Scale (KSS)
- Sleep Diary
- Simple PVT mode
- Basic Study framework
- Aviation Study framework
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The official NASA PVT+ (Psychomotor Vigilance Test) is a validated iOS based touchscreen PVT that includes multiple industry standard research forms for collecting a wide range of research data for sleep, alertness and performance studies. The app has three principle data collection schemes designed to accomidate a wide range of research studies. The Simple PVT: The Simple PVT is a single presentation of the Psychomotor Vigilance Test (PVT; described below). Participants can be instructed to take a PVT at any time. There is no limit to the number of PVTs that a participant can take. Basic Study: The Basic Study provides a single or multiday pre-set framework for collecting research data. Participants are prompted to complete a sleep diary after their main sleep episode. The participant is then prompted to complete three PVT and Karolinska Sleepiness Scale (KSS) responses during the day. The participants also complete a sleep diary before bed. Aviation Study: The Aviation Study provides a multiday pre-set framework for collecting aviation related research data. Split into Off-Duty Days and Duty Days. Participants are prompted to complete a sleep diary after their main sleep episode. The participant is then prompted to complete three PVT and KSS responses during off-duty days. On duty days, the participant is prompted to complete a PVT and KSS pre- and post-duty. They are also prompted to complete a PVT, KSS, hassle factors, use of fatigue countermeasures, and inflight rest at the top of descent for each flight. The participants also complete a sleep diary before bed. The number of flights within a duty day can be adjusted. The aviation study also includes a pre-study baseline questionnaires that can be completed at study enrollment. The specific components of the application include: - Psychomotor Vigilance Test (PVT): A simple reaction-timed test that is sensitive to sleep loss and circadian misalignment. The PVT displays a box on the screen and participants are instructed to tap the screen with their dominant thumb when a millisecond counter appears in the box and begins to count up. After the participant taps the screen, the counter briefly displays the reaction time in milliseconds, then the counter disappears, and the participant is instructed to refrain from touching the screen until the next millisecond counter appears in the box. The counter appears randomly every 2 to 10 seconds. The PVT can be configured by the investigator to the desired duration (currently validated for a 5-minute test). - Karolinska Sleepiness Scale (KSS): The KSS is a self-reported sleepiness rating where the participant is asked to rate their level of sleepiness within the last five minutes on a scale from 1 to 9. - Sleep Diary: The Basic Study and Aviation Study each include a sleep diary that the study participant is prompted to complete at the beginning and at the end of the main sleep episode. The pre-sleep sleep diary asks the participant to record any naps that were taken prior to the main sleep episode, along with indicating the time of bedtime. The post-sleep sleep diary asks the participant to record the time that it took to fall asleep, number and duration of night awakenings, final wake time, and a sleep quality rating. - Study Enrollment Information: The Aviation Study includes a demographic questionnaire and the Morningness-Eveningness Questionnaire along with a practice sleep diary and practice PVT to orient the participant to study procedures. Data collected from study participants using the NASA PVT+ iOS application does not include Personally Identifiable Information (PII). Research data is never collected directly by NASA unless a volunteer is participating in a NASA study. Data collected for research studies conducted outside of NASA, through use of the NASA PVT+ application, is never sent to NASA without a specific agreement between the outside organization and NASA.
Optimal HRV
This app uses heart rate variability (HRV) and biofeedback to help you manage stress and improve your body's ability to calm down. It offers guided sessions, personalized breathing rhythms, and real-time feedback to train your nervous system for better stress resilience.
- Real-time HRV data and biofeedback
- Personalized breathing rhythm identification
- Guided mindfulness sessions
- Daily check-ins and progress tracking
- External sensor integration for accuracy
- Multi-language support
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Are you feeling stressed, burned out, or just not yourself? Optimal HRV is the guided biofeedback app that teaches your body to calm down — for real. Backed by a Harvard Medical School mindfulness expert and trusted by athletes worldwide. Optimal HRV pairs real HRV data with live biofeedback, so every session trains your nervous system to handle stress better — not just tells you that you're stressed. Why HRV and Biofeedback Training Work Your Heart Rate Variability (HRV) is a window into how well your body handles stress, anxiety, and recovery — and biofeedback is how you train it to improve. Together, they show you what's happening inside your body, then guide you to change it in real time. With Optimal HRV, you can: • See how stressed — or relaxed — your body really is, using real HRV data. • Learn what actually helps you recover, from sleep to workouts to busy workdays. • Use live biofeedback to train your body to relax faster, right as it's happening. • Discover your own personal "perfect breathing rhythm" through guided sessions. Features You'll Actually Use • Daily Check-Ins — take a quick reading each morning, or anytime you want to see how you're doing. • Your Perfect Breathing Rhythm — a simple test finds the exact breathing pace that works best for you. • Live Feedback While You Train — a simple on-screen guide shows you when you're doing it just right. • Calming Mindfulness Sessions — guided practices created with a Harvard Medical School mindfulness expert, covering stress, anxiety, pain management, athletic performance, and more, with calming narrations in your choice of voice. • Easy-to-Read Progress — see your trends over days, weeks, and months, no data expertise needed. • Video Tutorials — learn HRV concepts and techniques at your own pace. • Make It Yours — adjust sounds, pacing, and reminders so training fits your life. • Available in 14 Languages — use Optimal HRV in your native language. • Device Testing — quickly verify if your heart rate monitor works with the app. • Great for Teams Too — employers and coaches can track group wellness together (Dashboard access needed). Why Optimal HRV Works with External Sensors (Not Apple Watch) We choose precision over convenience. Apple Watch is great for daily wellness, but Optimal HRV is built for serious HRV training. That's why we connect directly to an HRV monitor via Bluetooth — they deliver millisecond-accurate R‑R intervals that wrist sensors can't match. What that means for you: • More accurate data – better insights, better decisions. • Real-time streaming – no gaps, no guesswork. • Reliable results – trusted by athletes and coaches worldwide. Love Optimal HRV? Leave a review and help others find their calm. Your feedback helps us improve and reaches more people who need stress relief. Try it free for 30 days and feel the difference for yourself. Download now and start training your nervous system today. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is rating: NASA PVT+ at 4.8 against Optimal HRV's 3.0. NASA PVT+ also leads on in-app purchases (none vs 3) and review sentiment (25% vs 17%). Optimal HRV's advantage is update cadence (fortnightly vs every 3 months). On price, ratings volume, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Optimal HRV sells 3 in-app purchases, starting at $9.99 per month. NASA PVT+ asks for nothing beyond the download.
NASA PVT+ holds the better App Store score, 4.8 against 3.0. Both are backed by a comparable volume of ratings — 10 and 24 respectively. Written reviews point the same way: 25% of NASA PVT+'s written reviews are positive against 17% of Optimal HRV's.
NASA PVT+ ships an update every 3 months, Optimal HRV fortnightly. The most recent releases landed on October 27, 2026 and October 29, 2026 respectively.
| Parameter | NASA PVT+ | Optimal HRV |
|---|---|---|
| Price | Free | Free |
| Rating | 4.8 (10 ratings) — better | 3.0 (24 ratings) |
| Positive reviews | 25.0% of reviews — better | 16.7% of reviews |
| Number of ratings | 10 | 24 — better |
| Update frequency | Every 3 months | Fortnightly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 13.6 — better | 15.0 |
| Further details — not scored | ||
| Size | 31 MB | 57 MB |
| Age rating | 4+ | 4+ |
| Developer | NASA | Optimal, LLC |
Customer experience
NASA PVT+
Optimal HRV
In-app purchases
NASA PVT+
No in-app purchases
Optimal HRV
- 1 month1 Month trial$9.991 Month
- 6 Month1 Month trial$47.996 Months
- One Year1 Month trial$59.991 Year









