Awakening and counterregulatory response to hypoglycemia during early and late sleep.
Level 2 - randomized trial
Controlled crossover experimental trial in humans
PubMed 17400929 · doi:10.2337/db07-0044
What was done
Sixteen healthy subjects were tested across three conditions: insulin-induced hypoglycemia (linear fall to a nadir of 2.2 mmol/l over 60 min) immediately after sleep onset (early sleep), hypoglycemia after approximately 3.5 h of sleep (late sleep), and a control night without induced hypoglycemia. Awakening frequency and counterregulatory hormone responses (epinephrine, norepinephrine, ACTH, cortisol, and growth hormone) were compared.
What was found
During early sleep, 10 subjects awoke during hypoglycemia versus 0 in the control night (P < 0.004). During late sleep, all 16 subjects awoke during hypoglycemia versus 4 during the control night (P < 0.001). Increases in epinephrine, norepinephrine, ACTH, cortisol, and growth hormone were distinctly weaker during late sleep hypoglycemia compared to early sleep hypoglycemia (all P < 0.05). Exact hormone concentrations were not reported in the abstract.
Why it matters
This study shows that endocrine counterregulation to hypoglycemia diminishes during late nocturnal sleep, providing a physiological explanation for why diabetic patients frequently experience severe hypoglycemic episodes in the late night.
Limits
The study had a small sample size (n = 16) and was conducted exclusively in healthy individuals rather than patients with diabetes, whose counterregulatory systems may already be impaired. Specific hormone values and sleep stage correlations were not detailed in the abstract.
Cited by
- partial Waking up around 3:00 a.m. is caused by adrenaline being released to mobilize liver glycogen when nocturnal blood sugar drops.