Effects of Circadian Rhythms and Sleep Deprivation Vary Across Brain Regions

Lack of sleep can affect the brain and reduce work performance. A new study explains how the brain is locally affected by internal time of day and sleep-wake cycles.

Highlights

Sleep deprivation can affect the brain activity
Brain regions are affected differently by sleep deprivation and circadian rhythms
Study explains why a sleep deprived person struggles to pay attention to the job

Sleep is essential for a person's mental and physical health. Sleeping for seven to eight hours a day helps the brain function better. When a person does not get enough sleep, the condition is called as sleep deprivation. According to the Centers for Disease Control and Prevention, 7% to 19% of the adults in the United States do not get enough sleep every day.

Consequences of Sleep Deprivation

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Circadian rhythm (also known as sleep/wake cycle or the body clock) is a biological process that follows an internal cycle of roughly 24 hours.

‘Circadian rhythm and lack of sleep both have an influence on brain function. But, its effects vary across different regions of the brain.’

Sleep deprivation increases the risk of some health problems such as

1. Weight gain
2. Poor immune function
3. High blood pressure
4. Irregular heartbeat
5. Loss of productivity
6. Stress
7. Inability to concentrate

Sleep Deprivation and its Effect on Brain

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Staying awake for a day, a night and another day can take a toll on your brain. To study the effect of sleep loss on the brain, a team of researchers from the University of Liege and the University of Surrey conducted a study.

The researchers scanned the brains of 33 participants after a two-day sleep deprivation period and following recovery sleep. Each participant underwent 13 brain scans - twelve during sleep deprivation period and one following recovery sleep.

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The brain scans revealed activity in several regions of the brain, particularly in the subcortical areas, followed by a 24-hour rhythmic (circadian) pattern varied across the brain regions. The frontal brain areas showed a reduction in the activity with time awake followed by a return to pre-sleep deprivation levels after recovery sleep. Other brain regions displayed a combination of a rhythmic pattern and a decline associated with time awake. The researchers also found that these effects of sleep loss on the brain activity were widespread when the participants performed a simple task compared to a more complex memory dependent task.

The brain responses and the prominent circadian rhythm component explained the complexity of the mechanisms by which the brain responds to sleep deprivation. The brain function is influenced by the duration of wakefulness and circadian rhythm (biological time of day).

Sleeping Disorders
How many times have you stayed awake in the dead of the night counting sheep? If it is fairly often then you could be suffering from a sleep disorder!

Sleep deprivation does not reduce the performance during the day, but, it reduces rapidly during the biological night and improves the next day. The level of brain responses was assessed by functional Magnetic Resonance Imaging (fMRI) which provides measures of brain activity. fMRI also revealed that effects of sleep deprivation and the time of day varies across brain regions.

Professor Derk-Jan Dijk from the University of Surrey, said, "It is very gratifying to see directly at the level of fMRI-detected brain responses that circadian rhythmicity and lack of sleep both have such a profound influence on brain function. Our data may ultimately help us to better understand how the brain maintains performance during the day, why many symptoms in psychiatric and neurodegenerative conditions wax and wane, and why in the early morning after a night without sleep we struggle to maintain attention, whereas in the evening it is not an issue."

Vincenzo Muto from the University of Liege, said, "Our data highlights the complex interaction between our biological clock and time spent awake at a regional brain level: extremely intriguing!"

Pierre Maquet from the University of Liege added, "These results suggest the fascinating hypothesis that brain function is continuously modulated by two factors that are both globally expressed but locally modulated: sleep pressure and circadian rhythmicity."

The study is published in the journal Science .

Tips to Sleep Better

1. Set fixed bedtime
2. Turn off TV and mobile one hour before bedtime
3. Avoid caffeinated beverages
4. Exercise
5. Have a light dinner

Source-Medindia