A new study into the effect of light exposure therapy, coupled with a steady sleep schedule and dark glasses, allows for increased alertness during night shifts and a decent sleep during days off. The study is published in the December edition of Sleep.
The number of people who work in our 24 hour society is increasing. Shift work has always been associated with doctors, nurses, pilots, and the police and emergency services. It also draws in people involved in catering, shop work, driving and distribution, and manufacturing.
Shift work has long been associated with a number of health-related issues such as gastric upset, increased risk of cardiovascular disease, drowsiness, accidents and sleep disturbances. As shift work seems here to stay, anything that can reduce its negative effect, is a positive step.
Twenty-four volunteers were involved in a study that simulated seven night shifts between 11 p.m. to 7 a.m. with two days off. Sleep was scheduled between 8:30 a.m. to 3:30 p.m. after the first two nights, then reduced to finish at 1:30 p.m. after night three, and reduced to 12 p.m. on the two days off, the final four shifts returned to the 8:30 a.m. to 3.30 p.m. pattern. Every night shift the volunteers were exposed to five, 15-minute, intermittent bright light pulses; wore dark glasses when outside; and were exposed to the light every afternoon.
Mark Smith, lead author and a post-doctoral fellow at the Biological Rhythms Research Laboratory at Rush University Medical Center in Chicago, is reported in ScienceDaily as saying, "the major finding of this study was that complete physiological adaptation to a night shift and day sleep schedule does not appear necessary in order to improve night shift alertness and lengthen daytime sleep."
The effect of the research was to establish a compromise to the disruption of the natural body clock. When the experimental volunteers were compared to a control group they showed a level of performance close to that achieved on day shifts, with fast reaction times, little variability and few lapses. The control group demonstrated longer and more variable reaction times on all night shifts.
Significant differences between the experimental and control groups were also noted in their biological reactions. Dim light melatonin onset (DLMO) in the control group was around 4.30 a.m. In the control group, DLMO was around 12.30 p.m. The significance of these findings is that the sleepiest circadian time, measured by minimum body temperature, occurs within seven hours after the DLMO. The aim of the study was to find a way of delaying the sleepiest circadian time so that it fell within the sleep episodes after night shifts and on days off.
American Academy of Sleep Medicine (2008, December 8). How Shift Workers Can Improve Job Performance And Implement Realistic Sleep Schedule. ScienceDaily. Retrieved December 11, 2008, from http://www.sciencedaily.com/releases/2008/12/081201082003.htm