How can fatigue affect the outcomes of the SFST?

Fatigue can significantly influence a person’s performance on the Standardized Field Sobriety Test (SFST) by mimicking or exacerbating the signs of impairment that are typically associated with alcohol or drug use. When a person is fatigued, their cognitive function and physical coordination can be impaired. This includes reduced reaction times, difficulty concentrating, and a lack of balance and coordination—all of which are critical when performing the tasks involved in the SFST.

Since the tests are designed to gauge an individual's ability to perform tasks that require focus and physical stability, being fatigued may lead to similar errors to those seen in an impaired individual. Consequently, an officer might misinterpret the effects of fatigue as indicative of alcohol or drug impairment. This is why recognizing the impact fatigue can have on performance is essential for ensuring accurate assessments during sobriety tests.