The impact of breaking up prolonged sitting on glucose metabolism and cognitive function when sleep is restricted

Abstract

Objectives To investigate the acute benefits of breaking up prolonged sitting with light-intensity physical activity on (i) glucose metabolism under conditions of sleep restriction, and (ii) cognitive deficits associated with sleep restriction. Methods This counterbalanced, crossover trial consisted of two five-day (5 night) experimental conditions separated by a two-week washout period. On the first night, participants were given a 9-h sleep opportunity to allow the collection of steady-state baseline measures the following day. This was followed by three consecutive nights of sleep restriction (5-h sleep opportunity). In the sitting condition (SIT), participants remained seated between 1000 and 1800 h. In the physical activity condition (ACT), participants completed 3-min bouts of light-intensity walking every 30 min on a motorised treadmill between 1000 and 1800 h. At all other times, in both conditions, participants remained seated, except when walking to the dining room or to use the bathroom (max distance = 32 m). Six physically inactive, healthy males were randomised to one of two trial orders, 1) SIT then ACT, or 2) ACT then SIT. Continuous measures of interstitial glucose were measured at 5-min intervals. A cognitive and subjective test battery was administered every two hours during wake periods. Analyses were conducted using a series of linear mixed-effect ANOVAs. Results No differences in interstitial glucose concentration or cognitive performance were observed between the SIT condition and the ACT condition. Participants reported higher levels of sleepiness, and felt less alert in the SIT condition compared with the ACT condition. Conclusions There were no observable benefits of breaking up prolonged sitting on glucose metabolism under conditions of sleep restriction. These findings have implications for behaviour change interventions. Future studies will need to include larger, less homogenous study populations and appropriate control conditions (i.e., 8–9 h sleep opportunities).

The Association of Sedentary Behaviour and Cognitive Function in People Without Dementia: A Coordinated Analysis Across Five Cohort Studies from COSMIC

“…Longitudinally, no associations between SB and the rate of cognitive decline were found. This was unexpected given recent studies reported short-term and long-term detrimental effects of SB on the brain [25,46], although other studies could not establish an association between SB and cognition [24,47].…”

“…For example, in an experiment with 9 overweight adults, reduced cognitive performance was seen after 6 h of uninterrupted sitting compared to intermittent bouts of standing [25]. In contrast, no beneficial effects were found on cognitive performance by either interrupting an 8-h sitting period among 6 healthy males [24], or 7-h sitting period among 19 overweight adults [23]. In their review of observational studies examining the long-term effects of SB on cognition, Falck et al found associations between higher SB levels and lower cognition levels in six of the eight studies they reviewed [26].…”

“…Besides these cardiovascular risk factors, that might underlie an association between SB and cognitive decline, also acute effects of SB related to vascular health and cerebral blood flow might be involved [22]. However, to date, experimental mechanistic studies on these acute effects of SB on cognition show conflicting findings [23][24][25]. For example, in an experiment with 9 overweight adults, reduced cognitive performance was seen after 6 h of uninterrupted sitting compared to intermittent bouts of standing [25].…”

Exercise before bed does not impact sleep inertia in young healthy males

“…Participants were also required to have a BMI < 30 kg m −2 , and to be moderately morning/evening or neither chronotype on the Horne–Ostberg Morningness/Eveningness Questionnaire (Horne & Ostberg, ). These are standard inclusion criteria that have been used in previous sleep investigations (Sprajcer et al., ; Vincent, Jay, & Sargent, ). The majority of participants (11/12) normally performed regular exercise between 12:00 and 18:00 hours, with one participant preferring morning exercise 09:00–12:00 hours.…”

Breaking Up Sitting with Light-Intensity Physical Activity: Implications for Shift-Workers

“…This is important, as short sleep duration is associated with negative changes to the same metabolic and inflammatory markers that are positively influenced by breaking up sitting. As such, it is possible that short sleep durations may attenuate the positive impacts of breaking up prolonged sitting [ 36 ]. Therefore, more physical activity during breaks may be required (either longer durations of physical activity and/or higher intensity, e.g., MVPA rather than light-intensity physical activity) to get the same effect on physiological parameters in shift workers.…”