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Updated: Jun 13, 2026

Through-the-Wall Blood Sampling Method to Minimize Sleep Disruption in Clinical Settings
Published on: June 13, 2025
Sleep restriction is associated with increased morning plasma leptin concentrations, especially in women
Norah S Simpson1, Siobhan Banks, David F Dinges
1Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA. nssimpso@bidmc.harvard.edu
Study Objectives:
We evaluated the effects of sleep restriction on leptin levels in a large, diverse sample of healthy participants, while allowing free access to food.
Methods:
Prospective experimental design. After 2 nights of baseline sleep, 136 participants (49% women, 56% African Americans) received 5 consecutive nights of 4 hours time in bed (TIB). Additionally, one subset of participants received 2 additional nights of either further sleep restriction (n = 27) or increased sleep opportunity (n = 37). Control participants (n = 9) received 10 hr TIB on all study nights. Plasma leptin was measured between 10:30 a.m. and 12:00 noon following baseline sleep, after the initial sleep-restriction period, and after 2 nights of further sleep restriction or recovery sleep.
Results:
Leptin levels increased significantly among sleep-restricted participants after 5 nights of 4 hr TIB (Z = -8.43, p < .001). Increases were significantly greater among women compared to men (Z = -4.77, p < .001) and among participants with higher body mass index (BMI) compared to those with lower (Z = -2.09, p = .036), though participants in all categories (sex, race/ethnicity, BMI, and age) demonstrated significant increases. There was also a significant effect of allowed TIB on leptin levels following the 2 additional nights of sleep restriction (p < .001). Participants in the control condition showed no significant changes in leptin levels.
Conclusions:
These findings suggest that sleep restriction with ad libitum access to food significantly increases morning plasma leptin levels, particularly among women.
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