First Night Effect

Definition - What does First Night Effect mean?

First night effect (FNE) is a natural phenomenon that occurs during polysomnography (sleep study) testing where the patient experiences unihemispheric vigilance (partial wakefulness) on one side of the brain due to an unfamiliar environment. Medical evidence suggests that FNE is a physiological response or innate survival mechanism against perceived dangers or threats from new surroundings in which the left side of the brain is alert to external stimuli while the right side sleeps.

WorkplaceTesting explains First Night Effect

Adenosine is a biochemical agent the brain produces cumulatively throughout the day, maintaining circadian rhythm cycles that prompt the body for sleep. However, disruptive sleep patterns lend to the quality of sleep an individual receives, compounding the amount of sleep debt that develops over time. Consequently, a buildup of adenosine causes an individual to feel lethargic, carrying significant health and safety implications where cognitive functionality and motor coordination is impaired.

In the workplace, frequent traveling is a requirement for many jobs in which exposure to different time zones can be problematic for people with certain sleep disorders. For instance, FNE can exacerbate symptoms related to sleep apnea, but a portable continuous positive airway pressure (CPAP) device serves as an effective therapeutic modality to regulate breathing cycles conducive to sleep. People can offset FNE and concomitant sleep debt by following a regular sleep/wake schedule where their biorhythms conform to environmental conditions through exposure to natural light, setting a comfortable temperature in a room, and using white noise devices (i.e., radio static) to reduce sleep disturbances.

Proper sleep hygiene is imperative to help sustain normal biorhythms against FNE episodes common to employees who incur sleep debt from an erratic work routine. For employers, sleep deprivation hampers productivity, leading to significant financial constraints where healthcare liabilities escalate. Polysomnography testing can assess biological and physiological variables including blood oxygen levels, eye/leg movements, and respiration to determine to what extent FNE interferes with an individual’s capacity to fall asleep.

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