Table 1 Key Points

 1. Time spent in bed with low energy expenditure can be separated into three components: sedentary behavior, sleep-related behavior, and sleep.

 2. Sleep-related behavior includes sleep onset latency (SOL), wakefulness after sleep onset (WASO), and wake time after sleep offset (WASF).

 3. Though sleep-related behaviors would be currently classified as sedentary behavior (low energy expenditure, waking behavior in a lying position), we contend that sleep-related behaviors belong in the sleep domain; they are a normal part of a healthy sleep-wake cycle, are not a target for sedentary behavior reduction, and, when occurring in excess, likely increase health risk through distinct pathways (i.e., insufficient sleep duration or quality) from sedentary behavior.

 4. For research using thigh-worn inclinometers and 24-h wear protocols, diaries that ask participants to report ‘time got into bed’ and ‘lights out’ as well as ‘time woke up and stopped attempting sleep for the final time’ and ‘time got up for the day’ are crucial for allowing researchers to separate sedentary time accumulated in bed from sleep-related behaviors and sleep.