A new study supports the notion that making mundane tasks more complex can help minimize the effect of sleep deprivation
It is very well established that accuracy on a psychomotor vigilance task (PVT) deteriorates with increasing time spent awake (the PVT is administered as a boring task requiring the test taker to respond to a randomly occurring light on a screen). The PVT is a very sensitive measure of cognitive deterioration that occurs with increasing sleep deprivation. In a group of healthy volunteers who were sleep deprived for 40 hours, there was the expected deterioration in PVT. But surprisingly performance on more complex cognitive tasks that tested complex attention and working memory were unimpaired by the sleep deprivation. Several messages can be derived from this study:
- Simpler tasks with less cognitive load are the first affected by sleep deprivation
- More complex tasks are unaffected after 40 hours of sleep deprivation (although prolonged sleep deprivation will affect these tasks as well)
This may explain why a surgeon who is sleep deprived is relatively unaffected and performs the surgery safely but a driver on a dark highway driving an automatic car with nothing to distract his attention is likely to be in more danger of an accident.
The lesson is: Making even simple tasks more complex will act as a buttress against sleepiness induced deterioration in performance. This may be why drivers in Indian cities where traffic intrusions are unpredictable suffer fewer accidents compared to the same drivers on some of the newly constructed freeways in India.
The wake maintenance zone shows task dependent changes in cognitive function following one night without sleep; William R McMahon Sleep, zsy148, https://doi.org/10.1093/sleep/zsy148
Impaired sleep is associated with low testosterone
As men grow older levels of the male sex hormone testosterone fall. Falling testosterone levels are associated with a reduction in muscle and bone mass and an increase in fat deposition in the trunk. As a result, testosterone replacement therapy is recommended, at least in instances where testosterone levels fall well below the normal range.
An analysis of data collected in 2011-2012 as part of the National Health and Nutrition Examination Survey (NHANES) showed a correlation between reduction in sleep duration and testosterone levels – for each hour of reduction in sleep time, testosterone levels fell by 5.85 ng/dl. Whether an intervention that increases sleep duration will reverse the fall in testosterone levels is still an open question. If causation can be proven between sleep duration reduction and testosterone level reduction it will be just another reason among the many for men to get 7 hours or more of sleep each night!