Staying up all night consumes as much energy as walking 3km

It's not surprising that the time you're awake and active consumes more energy between sleeping and waking up, but what exactly is the metabolic cost of sleeping overnight and staying up all night? Is there a difference?

Even though I was in bed, I couldn't sleep easily, or when I gave up sleeping and read a book, the morning came ... Even if I didn't get out of bed and didn't move my body all night. An experiment conducted at the University of Colorado at Boulder revealed that it consumes extra energy by walking a little less than two miles (about 3.2 km) compared to sleeping overnight.

Metabolic Cost of Human Sleep Deprivation Quantified by University of Colorado Team | CU Boulder Today | University of Colorado Boulder
https://www.colorado.edu/today/2011/01/03/metabolic-cost-human-sleep-deprivation-quantified-university-colorado-team

The study by Dr. Kenneth Wright, an associate professor of physiology at the University of Colorado at Boulder, is the first to quantify the metabolic costs of human sleep. The paper is published in the Journal of Physiology .

In the experiment, eight young adult subjects were asked to spend three days in the laboratory without leaving their beds and to eat the exact same menu at exactly the same time for all three days. The amount of food was adjusted to the energy requirement of each subject.

During the three-day experiment, we asked them to wake up for 16 hours, then sleep for 8 hours, then wake up for 40 hours, and then sleep for 8 hours. In other words, it is a common 'overnight all night' pattern, where the first day is a normal eight-hour sleep, the second day is all night, and the third day is awake at dawn and sleeps at the same time as the first day. I had them spend all night reading, watching movies, and having conversations without moving from bed.

As a result, the energy consumed during the eight hours of staying up all night in bed was about 135 kcal more than when sleeping for eight hours. 'Some may wonder if this is the only energy saved by sleeping, but this was a higher number than we expected,' said Dr. Wright.

However, the extra energy consumed by the overnight stay is being regained in the day of the dawn. The energy consumed during the night on the second day of the experiment increased by up to 7% compared to when sleeping at night on the first day, but on the third night (40 hours of continuous awakening) on the 'recovery day'. It was said that it decreased by 5% in the remaining 8 hours sleep).

This seems to be related to the difference in quality of sleep between normal sleep and after all night. In the experiment, each stage of sleep such as from light sleep to REM sleep and non-REM sleep, and when waking up from sleep was observed, and it was suggested that the energy consumption was the highest at the stage of waking up naturally. Sleep on the recovery day after staying up all night has a lower frequency of awakening.

People with insomnia or sleep apnea may think that they can't sleep or wake up many times in the middle of the night, wasting energy, but the results of this study are also for sleep-disordered patients. Further research is awaited to see if this is the case.

'If the experiment allowed us to get out of bed and walk around all night, the metabolic costs of all night would have been higher,' said Dr. Wright. In the experiment, the diets taken by the subjects were strictly controlled, but it was found that lack of sleep reduced the hormone 'leptin ' that controls appetite, so if the diet was not restricted, the subjects stayed up all night. Is likely to have had a midnight snack. Also, if not awakened at the end of the experiment (after 8 hours of sleep on the 3rd day), many subjects would continue to sleep and 'regain' more energy.

'Why don't you save more energy during sleep is one of the mysteries about sleep. Sleep has many functions, and some of the energy saved by sleep is other physiological. I suspect it's being distributed to the process, 'says Professor Wright. The energy saved by resting the body is used for nighttime physiological activities such as strengthening the functions of the immune system and the connections of nerve cells in the brain, and synthesizing and secreting hormones. That is '135 kcal'.

Dr. Wright emphasizes that energy expenditure from sleep deprivation is 'neither effective nor safe' for weight loss, and that some studies link chronic sleep deprivation to cognitive impairment.