The coronavirus pandemic–induced lockdown has taken a toll on the sleep cycle of people across the globe. Several online surveys have shown that social media and unstructured work-time have altered millennial’s sleep-wake timings. Various behavioural and physiological consequences of sleep restriction have been studied and well-documented. A new study shows a direct link between sleep deprivation and brain and body temperature in rats.
Role of sleep
The experiments conducted in the lab revealed that not sleeping for 24 hours can increase the temperatures of the cortical and hypothalamus brain regions The cerebral cortex plays a key role in attention, awareness and memory; while the hypothalamus has various roles: regulating body temperature, sleep-wake cycle, food intake, sexual behaviour, releasing hormones and regulating emotional responses. Special temperature sensors were implanted into the brain and abdomen region of 10 adult male rats to monitor all the temperatures simultaneously at 15-second intervals. “We gently rocked the cage when we saw that the rat was falling asleep. This gentle handling method doesn’t induce much stress in the rats. Taking shifts, my team and I were able to keep the rats awake for 24 hours. The rats had adequate food and water in the cage, just that we didn't let them sleep,” explains Lal Chandra Vishwakarma, Research Associate at the Baldev Singh Laboratory for Sleep Research, Department of Physiology, All India Institute of Medical Sciences, New Delhi.
He is the first author of the paper recently published in the Journal of Sleep Research. After 24 hours, they were given a recovery sleep of 12 hours. Body and brain temperatures recorded during baseline conditions, sleep deprivation period and recovery sleep were then analysed. During the sleep deprivation period the temperature of the body, hypothalamic and cortical region was found to increase significantly. The recovery sleep was able to bring down the body and cortical temperature to the near-baseline value in about four hours. However, the hypothalamic temperature remained higher than the baseline values throughout the 12 hours of recovery sleep. This may be due to the fact that hypothalamus is the temperature regulating area of the brain.
“We propose that this rise in temperature may have an effect on cognitive ability. Acute sleep deprivation has also been reported to affect the mood, memory skills and attention in humans. Many times, we catch ourselves making an error in judgement when we don’t get proper sleep,” adds Hruda Nanda Mallick from the Department of Physiology, All India Institute of Medical Sciences, New Delhi. He is the corresponding author of the work. Neuromuscular changes The team is currently studying the impact of sleep deprivation on neuromuscular changes to prove the point that muscles are also a beneficiary of sleep. Dr Mallick adds: “Sleep is as important as nutrition and exercise. Although the core function of sleep is yet to be discovered, it serves many important functions which include, growth and repair, memory consolidation, energy conservation and boost immunity. I urge people to follow a strict sleep routine and to immediately consult a doctor if they have a problem falling asleep.”