Through-the-Wall Blood Sampling Method to Minimize Sleep Disruption in Clinical Settings

Physiological rhythms, including diurnal and circadian rhythms, play a critical role in health, with disturbances increasingly linked to cardiovascular disease and type 2 diabetes. These rhythms are closely tied to sleep-wake cycles, as changes in sleep timing or duration can alter diurnal and circadian rhythms, thereby disrupting physiological homeostasis. Additional factors, such as the timing of behaviors like food intake and/or physical activity, may modulate 24-h rhythms in manners that support health or promote chronic disease risk. Despite the growing recognition of the importance of biological rhythms, obtaining serial blood samples required to elucidate patterns in circulating factors remains a significant challenge in clinical research. Routine blood draw methods can be disruptive to sleep, potentially altering sleep and biological rhythms and subsequently influencing variables of interest. This underscores the need for minimally invasive approaches that allow for the assessment of 24-h biological processes without disturbing sleep or biological rhythms. To address these challenges, many clinical and research groups employ a technique known as a "through-the-wall" blood sampling method. This approach uses extended tubing connected to an indwelling catheter, threaded through a wall or partition to a location outside the participant's room. By enabling blood collection without having to enter the room, this method minimizes disruptions, thereby preserving the integrity of the 24-h profiles of circulating variables of interest and minimally disturbing sleep. Here, we provide a detailed description of the through-the-wall blood sampling method and demonstrate its feasibility and efficacy in collecting blood samples during scheduled sleep opportunities. Representative data from a clinical study are presented, and additional considerations, including the impact of a difficult blood draw on sleep architecture, are discussed.