Harvard Researchers Link Death from Sleep Deprivation to the Gut

A new study shows severe sleep loss leads to death by inducing the buildup of harmful, oxygen-containing molecules in the gut of flies, but antioxidant treatments restore lifespan.

Key Points

Sleep deprivation leads to the accumulation of harmful, oxygen-containing molecules (reactive oxygen species [ROS]) in the fly and mouse gut.
ROS buildup triggers DNA damage and cell death in the gut.
Preventing ROS buildup in the gut with antioxidant treatments allows flies to survive without sleep with a near-normal lifespan

About one-third of people don’t attain the Center for Disease Control’s recommended seven hours or more of sleep per night. At the same time, very few of us experience the paranoia and disorientation that goes along with extreme sleep deprivation. In rare circumstances, prolonged sleep loss leads to death, leading researchers to question why animals die when they don’t sleep.

Published in Cell, Rogulja and colleagues from Harvard Medical School demonstrate that sleep deprivation triggers harmful ROS buildup in the gut of flies and mice. The accumulation of ROS leads to a 50% reduction in average lifespan for the flies, but antioxidant treatment with pharmaceuticals like melatonin, lipoic acid, or nicotinamide adenine dinucleotide (NAD+) promotes survival without sleep. These findings suggest that using antioxidants may mitigate the adverse effects of sleep deprivation on the gut.

“We took an unbiased approach and searched throughout the body for indicators of damage from sleep deprivation. We were surprised to find it was the gut that plays a key role in causing death,” said senior study author Dragana Rogulja in a press release.

“Even more surprising, we found that premature death could be prevented. Each morning, we would all gather around to look at the flies, with disbelief to be honest. What we saw is that every time we could neutralize ROS in the gut, we could rescue the flies,” Rogulja said.

Sleep Deprivation Triggers Harmful, Oxygen-Containing Molecule Accumulation in the Gut

To figure out what organs sleep deprivation affects the most, the Harvard-based research team examined cell markers of damage throughout the body while flies were kept awake. Rogulja and colleagues genetically manipulated the flies so that neurons which facilitate wakefulness were stimulated only at temperatures exceeding 29^0C. At temperatures above 29^0C, they found that sleep-deprived flies’ guts exhibited increased ROS levels. The researchers used other methods such as mechanical agitation to keep the flies awake and obtained the same results showing ROS in the gut, suggesting gut ROS accumulation triggers death from extreme sleep loss.

(Vaccaro et al., 2020 | *Cell*) **ROS builds up in the gut specifically with sleep deprivation**. C) Dihydroethidium (DHE) intensity, denoting ROS accumulation, is greater in the guts of sleep-deprived flies. D) Higher DHE intensities as shown by brighter hues were seen toward the front (proventriculus) of the gut and the midgut in flies with sleep deprivation.

To then find out whether these findings in flies translate to mammals, Rogulja and colleagues tested whether sleep deprivation triggers ROS accumulation in the guts of mice. With mechanical stimulation, the mice were kept awake for five days. Following sleep deprivation, their organs were tested for ROS, and. Rogulja and colleagues found elevated ROS levels exclusively in the small and large intestines. These findings suggest that sleep deprivation-induced ROS accumulation in the gut extends from flies to mammals, namely, mice.

(Vaccaro et al., 2020 | *Cell*) **ROS accumulates in the gut of mice with sleep deprivation**. ROS (denoted with red hue) builds up in the small and large intestine but not the liver or brain after five days of sleep deprivation (5 days SD) compared to no sleep deprivation (Non-SD).

Antioxidants Rescue Survival Despite Sleep Deprivation

To then corroborate that the accumulation of harmful ROS in the gut from sleep loss leads to death, the research team tested whether treating with antioxidants promotes survival despite lost sleep in flies. The team identified 11 antioxidants, including melatonin, lipoic acid, and NAD+ that rescue fly lifespan during sleep deprivation. These findings provide further evidence that ROS accumulation in the gut from sleep deprivation can lead to death since neutralizing ROS with antioxidants rescues lifespan despite sleep loss.

(Vaccaro et al., 2020 | *Cell*) **Antioxidant treatment rescues lifespan in sleep-deprived flies and neutralizes ROS in the gut.** (Left) Sleep deprived flies (green line and squares) exhibit reduced lifespans, but antioxidant treatment with melatonin, lipoic acid, or NAD rescues survival. (Right) ROS (denoted with red hue) accumulate in the gut with no drug, but are suppressed with antioxidants.

“We still don’t know why sleep loss causes ROS accumulation in the gut, and why this is lethal,” said Kaplan Dor, one of the lead authors of the study in a press release. “Sleep deprivation could directly affect the gut, but the trigger may also originate in the brain. Similarly, death could be due to damage in the gut or because high levels of ROS have systemic effects, or some combination of these.”

Antioxidants May Amend Unhealthy Guts in People Who Lack Sleep

The findings from the study may aid in the development of therapies to offset the negative effects from sleep deprivation. Targeting harmful ROS accumulation in the gut may not only help people who don’t sleep enough have healthier guts, but it may also reduce the chances of diseases like colon cancer and type II diabetes, which are tied to not getting enough sleep.