An interventional study of Optimal Bedtime and Placebo in Sleep, Alertness, Fatigue, Mood, and Performance and Well-being, sponsored by Massachusetts Institute of Technology. Completed at 1 site in United States. Open to participants aged 18 Years to 60 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-23.
Sponsored by Massachusetts Institute of Technology · Not applicable, Interventional, and Other
The goal of this interventional study is to test whether circadian-informed bedtime recommendations can improve sleep, next-day psychomotor vigilance, and subjective well-being among healthy adults. The main questions it aims to answer are:
Researchers will compare Optimal Bedtime with a placebo bedtime and an unguided baseline in a cross-over design.
Participants will:
1,912 studies on the registry are indexed under Fatigue; 381 are open to participants now.
This study's enrollment of 203 is above the median of 53 across 1,479 interventional studies indexed under Fatigue.
Browse Fatigue studies →Massachusetts Institute of Technology is the lead sponsor of 34 studies on the registry; 11 are open to participants now.
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Exclusion Criteria:
Optimal Bedtime recommendation for two weeks followed by placebo bedtime recommendation for two weeks (randomized crossover)
Behavioral: Optimal Bedtime · Behavioral: Placebo
Placebo bedtime recommendation for two weeks followed by Optimal Bedtime recommendation for two weeks (randomized crossover)
Behavioral: Optimal Bedtime · Behavioral: Placebo
Optimal Bedtime recommendations informed by the estimated dim-light melatonin onset from a consumer smartwatch, adjusted for the desired total sleep time of the participant and delivered via a mobile application twice a day.
Also known as: Smart Bedtime
Placebo bedtime recommendations based on the desired total sleep time and desired wake-up time of the participant with a daily random jitter within ± 30 minutes, delivered via a mobile application twice a day.
Change from Baseline and Placebo in Total Sleep Time
Smartwatch-derived objective total sleep time in minutes.
Time frame: 6 weeks, nightly in baseline, placebo, and intervention.
Change from Baseline and Placebo in the Count of Lapse in Psychomotor Vigilance Task (PVT)
Count of responses with reaction time greater than 500 milliseconds in a PVT session.
Time frame: 6 weeks, daily in baseline, placebo, and intervention.
Change from Baseline and Placebo in Subjective Sleep Quality
Self-reported sleep quality score on a visual analogue scale of 0 to 100, higher indicating more favorable.
Time frame: 6 weeks, daily in baseline, placebo, and intervention.
Change from Baseline and Placebo in Sleep Efficiency
Objective total sleep time divided by time in bed, in percentage points.
Time frame: 6 weeks, nightly in baseline, placebo, and intervention.
Change from Baseline and Placebo in Sleep Fragmentation Index
Waking bouts per 100 min of objective total sleep time.
Time frame: 6 weeks, nightly in baseline, placebo, and intervention.
Change from Baseline and Placebo in Wake After Sleep Onset
Objective total time awake after sleep onset and before wake onset, in minutes.
Time frame: 6 weeks, nightly in baseline, placebo, and intervention.
Change from Baseline and Placebo in Deep Sleep Duration
Smartwatch-derived deep sleep duration in minutes.
Time frame: 6 weeks, nightly in baseline, placebo, and intervention.
Change from Baseline and Placebo in Deep Sleep Percentage
Smartwatch-derived deep sleep in percentage of objective total sleep time.
Time frame: 6 weeks, nightly in baseline, placebo, and intervention.
Change from Baseline and Placebo in Rapid Eye Movement (REM) Sleep Duration
Smartwatch-derived REM sleep duration in minutes.
Time frame: 6 weeks, nightly in baseline, placebo, and intervention.
Change from Baseline and Placebo in Rapid Eye Movement (REM) Sleep Percentage
Smartwatch-derived REM sleep in percentage of objective total sleep time.
Time frame: 6 weeks, nightly in baseline, placebo, and intervention.
Change from Baseline and Placebo in Mean Response Speed
Mean reciprocal reaction time in a PVT session, in per second.
Time frame: 6 weeks, daily in baseline, placebo, and intervention.
Change from Baseline and Placebo in Mean Slowest-10% Response Speed
Mean reciprocal reaction time over the slowest 10% responses in a PVT session, in per second.
Time frame: 6 week, daily in baseline, placebo, and intervention.
Change from Baseline and Placebo in Subjective Alertness
Daily self-reported alertness score on a visual analogue scale of 0 to 100, higher indicating more favorable.
Time frame: 6 weeks, daily in baseline, placebo, and intervention.
Change from Baseline and Placebo in Subjective Happiness
Self-reported happiness score on a visual analogue scale of 0 to 100, higher indicating more favorable.
Time frame: 6 weeks, daily in baseline, placebo, and intervention.
Change from Baseline and Placebo in Subjective Energy
Self-reported energy score on a visual analogue scale of 0 to 100, higher indicating more favorable.
Time frame: 6 weeks, daily in baseline, placebo, and intervention.
Change from Baseline and Placebo in Subjective Health
Self-reported health score on a visual analogue scale of 0 to 100, higher indicating more favorable.
Time frame: 6 weeks, daily in baseline, placebo, and intervention.
Change from Baseline and Placebo in Subjective Calmness
Self-reported calmness score on a visual analogue scale of 0 to 100, higher indicating more favorable.
Time frame: 6 weeks, daily in baseline, placebo, and intervention.
Plan to share: No
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Ran from Jun 2025 to primary completion in Jan 2026, 7 months.
Of 771 non-industry interventional studies with no phase under Fatigue, half reached primary completion within 12 months of starting (the median), counting those still running; a quarter within 5 and three quarters within 28. This study's 7 months is below that.
Counting every sponsor, half of 824 studies reached it within 12 months; a quarter within 5 and three quarters within 27.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Massachusetts Institute of Technology