Short-term sleep deprivation leads to decreased systemic redox metabolites and altered epigenetic status

Abstract

Sleep is critical for repair as well as the rejuvenation processes in the body and many of these functions are regulated via underlying cellular metabolic homeostasis. Changes in sleep pattern are reported to alter such metabolic function resulting in altered disease susceptibility or behavior. Here, we measured the extent to which overnight total sleep deprivation (SD) in young adult humans can influence systemic (plasma-derived) redox-metabolism including the major antioxidant, glutathione as well as DNA methylation levels. Nineteen participants (n = 19, μ age = 21, SD = 3.09) underwent morning testing before and after overnight total SD. Biochemical measures before and after SD revealed that glutathione, ATP, cysteine, and homocysteine levels were significantly reduced following one night of sleep deprivation (all p's < 0.01). Parallel to the well-recognized fact that sleep deprivation (maintaining wakefulness) uses up metabolic reserves, we observed that morning cortisol levels were blunted after sleep deprivation. There were no significant correlations between self-reported or actigraphy-measured sleep and the biochemical measurements, strongly indicating that prior sleep behavior did not have any direct influence on the biochemical measures taken at baseline or after sleep deprivation. Results from the current investigation supports the previous literature implicating the induction of oxidative stress and ATP depletion with sleep deprivation. Furthermore, such altered antioxidant status can also induce downstream epigenetic changes. Although we did not measure the specific genes that were altered under the influence of such sleep deprivation, such epigenetic changes could potentially contribute towards disease predisposition.

Fig 1. Redox-methylation pathway.

Methionine synthase contains a redox-active methylcobalamin cofactor. Under oxidative stress, this cofactor becomes oxidized, limiting methionine synthase activity and can affect the levels of global DNA Methylation Under these conditions, homocysteine can be condensed with serine to form cystathionine and then with cysteine to support GSH synthesis. Another source of the cysteine is through the Excitatory Amino Acid Transport (EAAT3), which is the major source of cysteine especially in the neuronal cells. Cellular redox state is indicated by the GSH/GSSG ratio.

Fig 2. Actigraphy measures.

Sleep behavior was objectively verified the week prior to sleep deprivation through actigraph monitoring. Top left: actigraphy-recorded time-in-bed confirmed that the participants generally adhered to the instruction to sleep 8 hours the week prior to sleep deprivation (mean = 8.03, SD = 1.12). Top Right: Total sleep actigraphy-recorded sleep time was 6 hours and 10 min (SD = 1.04). Bottom Left: The average sleep latency was 16 minutes (SD = 10.29). Bottom Right: the average sleep efficiency was 82.64% (SD = 4.71).

Fig 3. Thiol metabolite levels in plasma.

Thiol / Thioether metabolite levels were analyzed via HPLC with electrochemical detection before (BL) and after sleep deprivation (SD) in participants (Mean +/- SEM). GSH / GSSG ratio indicates oxidative stress. HCY—homocysteine, Cys- cysteine were measured in uM. ATP measurement. ATP was measured using commercially available kit and expressed in umol/ L of plasma. Asterisk indicates a significant difference from baseline * = p < 0.05, ** = p < 0.01.

Fig 4. Cortisol.

Moring cortisol levels were significantly lower after sleep deprivation (mean = 0.35, SD = 0.22) relative to the morning of baseline testing (mean = 0.63, SD = 0.24), t(18) = 6.61, p < 0.01.

Fig 5. DNA methylation levels.

Plasma samples were used to isolate cell free circulating DNA. The percentage of 5-methylcytosine and 5-hydroxymethylcytosine on isolated DNA was measured using an ELISA assay (Mean +/- SEM). Asterisk indicates a significant difference from baseline * = p < 0.05, ** = p < 0.01.