Lack of Sleep Increases Disease Risk
Staying up all night, sleeping all day can swiftly impact over 100 proteins in the blood
Adequate sleep is essential for a general healthy functioning
Staying awake all night and sleeping all day for just a few days can disrupt levels and time of day patterns of more than 100 proteins in the blood, including those that influence blood sugar, energy metabolism, and immune function, according to new University of Colorado Boulder research published in the journal PNAS this week.
"This tells us that when we experience things like jet lag or a couple of nights of shift work, we very rapidly alter our normal physiology in a way that if sustained can be detrimental to our health," said senior author Kenneth Wright, director of the Sleep and Chronobiology Laboratory and Professor in the Department of Integrative Physiology.
The study is the first to examine how protein levels in human blood, also known as the plasma proteome, vary over a 24-hour period and how altered sleep and meal timing affects them.
The findings could open the door to developing new treatments for night shift workers, who make up about 20% of the global workforce and are at higher risk for diabetes and cancer. It could also enable doctors to precisely time administration of drugs, vaccines and diagnostic tests around the circadian clock.
"If we know the proteins that the clock regulates, we can adjust the timing of treatments to be in line with those proteins," said lead author Christopher Depner, a postdoctoral researcher in the Department of Integrative Physiology.
The researchers recruited six healthy male subjects in their 20s to spend six days at CU's clinical translational research center, where their meals, sleep, activity and light exposure were tightly controlled. On days one and two, the men stuck to a normal schedule. Then they were gradually transitioned to a simulated night-shift work pattern, in which they had eight-hour sleep opportunities during the day and stayed up all night, eating
They found 129 proteins whose patterns were thrown off by the simulated night shift.
"By the second day of the misalignment we were already starting to see proteins that normally peak during the day peaking at night and vice versa," Depner said.
One of those proteins was glucagon, which prompts the liver to push more sugar into the bloodstream. When subjects stayed awake at night, levels not only surged at night instead of
The simulated night shift schedule also decreased levels of fibroblast growth factor 19, which has been shown in animal models to boost calorie-burning or energy expenditure. This fell in line with the finding that subjects burned 10% fewer calories per minute when their schedule was misaligned.
Thirty proteins showed a clear 24-hour-cycle, with the majority peaking between 2 p.m. and 9 p.m.
When it comes to diagnostic blood tests - which are relied upon more often in the age of precision medicine - "timing matters," said Wright.
Previous studies have looked at time-of-day expression patterns of protein-coding genes in specific organs. By studying the actual proteins in the blood, researchers can study a broader array and get a better picture of what's happening in real time, Depner said.
He and Wright note that they kept all the study subjects in dim light conditions so that light-exposure (which can also strongly affect the circadian system) didn't influence results. Even without the glow of electronics at night, changes in protein patterns were rapid and widespread.
"This shows that the problem is not just light at night," Wright said.
"When people eat at the wrong time or are awake at the wrong time that can have consequences too."
Restricting sleep below an individual's optimal time in bed (TIB) can cause a range of neurobehavioral deficits, including lapses of attention, slowed working memory, reduced cognitive throughput, depressed mood, and perseveration of thought. Neurobehavioral deficits accumulate across days of partial sleep loss to levels equivalent to those found after 1 to 3 nights of total sleep loss.