How your body deals with the time change
According to Colleen Carney, associate professor and director of the Sleep and Depression Laboratory at Toronto’s Ryerson University, your brain contains a central ‘clock’ called the suprachiasmatic nucleus, or SCN. This small region of the brain controls the circadian rhythm – the cycle that regulates your body temperature, digestive function, hormone release, and sleep/awake patterns. Unlike your watch or a clock on the wall, the circadian rhythm isn’t exactly 24 hours, so it relies on external cues such as daylight to set it. One of the main pathways for these cues is through the eye. “Cues can be simple things like the timing of light, when you get in and out of bed, the timing of meals – they’re important factors that actually set the clock and keep it running,” says Carney.
When daylight savings time occurs in the spring, and an hour of sleep is lost, the daily cues are altered, and your internal rhythm drifts. “[This change] affects your mood, hunger, sleep, fatigue levels and alertness,” explains Carney. For most people with regular sleep patterns, it takes about a day for the circadian rhythm to re-adjust to daylight savings time and the lost hour. You may feel sluggish, foggy brained and hungry, but these feelings will be short lived, and won’t cause permanent harm. For certain individuals, however, this time shift can prove extremely challenging, with the uncomfortable effects lingering for a while.