Any people that are in studies, are in hospital and wake and sleep around the hospital times anyway.   For example they may have studied the people that had been used to correlate the dtata on the Mayo chart over 3-4 days and had them hooked up to drips and in hospital.  Who has not been in there and slept like they would at home--especially woth a drip hooked up and bloods being taken every hour or so.  In the Hospitals we have used it is lights out at a certain time and then also, you get waken with the trolleys at between 7-8am.  ;) LOL--big cortisol surge as you get angry cos you wanted to sleep longer.