Reducing Sleep Inertia with Reactive Countermeasures: Impact of Light, Odor and Caffeine on Alertness
Abstract
Background and rational: ‘Sleep inertia’ is associated with a feeling of grogginess, confusion, cognitive slowing, impaired memory processes, and increased vulnerability to errors on waking. In operational settings, personnel are required to perform safety-critical tasks and make important decisions immediately upon waking. Chronic sleep restriction and fatigue, which is common in operational, 24/7 environments, also worsens sleep inertia, creating a scenario where the level of cognitive impairment on waking can increase daily. Sleep inertia can therefore pose a safety risk and impact mission success. Countermeasures that reduce sleep inertia, reactive countermeasures, could be used to minimize the effect of sleep inertia on cognitive performance. These countermeasures need to be operationally relevant and easily deployable on ships, submarines, and other high tempo workplace environments. Three types of reactive countermeasures that warrant further investigation are light – a core environmental signal for biological alertness, odor – a novel alerting stimulus, and caffeine – the most commonly used countermeasure for sleepiness. Specific aims and objectives: The objective of this study is to investigate the following aims: Aim 1: Evaluate the impact of sleep inertia on cognitive performance and subjective sleepiness/fatigue, measuring overall impairment and time course, during the first hour after waking at 0400h and 1600h, relative to baseline performance, across days of sleep restriction. Aim 2: Determine the effectiveness of reactive countermeasures (caffeine, odor, and bright light) to reduce the impact sleep inertia on cognitive performance and subjective sleepiness/fatigue, measuring overall impairment and time course, during the first hour after waking at 0400h and 1600h, relative to baseline performance, across days of sleep restriction. Study design: Twenty-four participants will undergo a four condition, between group sleep restriction study. Participants will be randomized to one of four conditions 1) Odor 2) Bright light 3) Caffeine or 3) Control. Following a baseline sleep of seven hours, participants will have their sleep restricted to five hours per day for four experimental days. This period will comprise of a four-hour night sleep and a one-hour afternoon sleep. Upon completion of the four experimental days participants will be given a 10-hour recovery sleep period. Immediately upon wakening from each sleep, participants’ performance will be assessed with a one-hour cognitive behavioral test battery to examine the impact of sleep inertia on performance. The four-day treatment phase will allow for the investigation of the cumulative impact of the sleep deprivation on sleep inertia and the effectiveness of the sleep inertia countermeasure. Impact: The study focuses on the effects of sleep restriction and sleep inertia on cognitive performance at levels commonly experienced by individuals working in 24/7 industries. The knowledge gained could help establish sleep schedules for maintaining optimal performance in 24/7 operations and identify countermeasures that could be used in the workplace to improve safety and productivity. Data from this study will help inform health and safety public policy decisions pertaining to hours of work and rest in many occupations which sleep restriction poses significant risks to health and safety.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 23, 2021
- Source ID
- N002442110006
Entities
People
- Siobhan Banks
Organizations
- United States Navy
- University of South Australia