A control group working under the same supervisor or under two supervisors who were evaluated equally had a difference of only 3 mm Hg in the systolic blood pressure and no significant rise in the diastolic blood pressure.
The study originates from Buckinghamshire Chilterns University College and the authors conclude that such a sustained elevation in blood pressure increases the risk of heart attacks by 16% and the risk of stroke by 33%.
N Wager, G Fieldman, and T Hussey. The effect on ambulatory blood pressure of working under favourably and unfavourably perceived supervisors. Occup Environ Med 2003 60: 468-474.