Our overtired brains are turning to microsleeping

Analysis of brain activity shows that we may not even be aware of a ‘waking sleep’


It’s quite scary when it happens. Suddenly you jerk back to full consciousness realising that, for a second or two, your mind had closed down.

At least you think it was a second or two…

A study published in the journal Neuroimage showed the brain activity of a group of volunteers who were sleep deprived for 22 hours and then placed in a darkened MRI machine and told not to fall asleep.

As the subjects nodded off involuntarily the scanner picked up areas of activity during their microsleeping.

In each case there was reduced activity in the thalamus, a region of the brain associated with controlling sleep.

At the same time there was actually an increase in the activity around the parts of the brain that process sensory information (sight, hearing, touch etc) which are most associated with alertness and cognition.

Effectively one part of the brain was fooling the other into thinking it was awake even as it was shutting down.

This makes the consciousness a very unreliable witness as to the real length of any microsleep that occurs. We may feel that we nodded for only a second but it is equally likely that our brains felt it necessary to shut down for far longer before the active parts of the brain regain control.

The results echo a 2011 study by the University of Wisconsin that found that some nerve cells in a sleep deprived brain were able to shut themselves down even while the rest of the brain was awake.

All the data from this area of study suggests that different parts of the brain are affected to different degrees by a lack of sleep and that consciousness is not a simple matter of being awake or asleep.

Once we have become overtired there is a constant struggle between the various areas of the brain to achieve some downtime and certain regions seem to be able to achieve a shut down without the other parts being able to prevent it.

A survey by a UK road safety charity revealed that some 45% of men and 22% of women were aware of microsleeping while they were driving.

Aside from the sheer debilitating effect of fatigue, these studies suggest that we are capable of fooling ourselves into thinking we are able to handle a lack of sleep because we don’t feel ‘tired’ in the traditional sense.

At the first sign of drowsiness we should admit to ourselves that there is a danger and not believe that we can consciously will ourselves into a more wakeful state.

Especially when driving.



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