Table 1.

Brigham and Women’s Hospital Division of Sleep and Circadian Disorders Intensive Physiological Monitoring unit studies: psychologically relevant concerns.

1. Restrictions in activity level (e.g., light stretching only, no strenuous exercise, no formal meditation as this can drive metabolic output in two directions, therefore, people must be prepared to limit these activities as these are not variables we are testing) (e.g., no exercise or activities that change heart rate, no meditation, no lying down during the daytime)

2. Absence of time cues (e.g., no windows in study rooms; no clocks, watches, timers; no live television, radio, internet)

3. Acute and chronic sleep loss and sleep distribution A. Acute sleep deprivation ● e.g., >18 h continuous wake periods B. Chronic sleep deprivation: ● e.g., <7 h in a 24-h period over many days C. Sleep disruption: ● e.g., sleep scheduled at times when it is difficult to fall asleep or remain asleep

4. Lighting intensity and exposure variations during sleep A. Dim light (e.g., <4 lux) B. Bright light (e.g., >500–10,000 lux) C. Complete darkness (scheduled sleep episodes throughout)

5. Prolonged sedentary behavior A. Specialized circadian assessment—sitting in bed for extended time periods (e.g., procedures that last 16–50 h, no vertical position as it can impact blood pressure which is one of the time cues)

6. Limited autonomy A. Investigators monitor and control physiological functions according to precise schedules B. Timing and duration of meals and showers is limited by protocol demands C. Inflexibility of meal content once dietitians have prepared menu D. Frequent interruptions of free-time for study-related events

7. Limited outside communication A. No direct contact with friends, family, and significant others for the extent of their study B. Limited communication in the form of letters (no email, calls, etc.) C. Regular engagement with supportive trained staff only