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Waking when it’s still dark – why is it so hard?

By Dr. Ruth Leong

Healthcare workers have an earlier start than most, often having to get up while it’s still dark. This is especially true for House Officers who must update the list of patients and pre-round before the rest of team comes in.

Even if one slept early the night before and got 7-8 hours of sleep, getting up at 5am while it’s still dark outside is challenging and wearisome. It just doesn’t feel right to get dressed for the day when the sky is still dark and unyielding. Strangely, on the other hand, waking at 8am even if one had much less sleep the night before doesn’t feel as bad. Why?

Sleep is governed by two main processes: (1) the homeostatic sleep drive, a function of time spent awake and (2) the circadian arousal drive, or the “internal body clock”. It is the second of the two that explains why it is so hard to wake in the early morning when it’s still dark outside.

Alerting signals are released at different intervals across the day according to our internal body clocks, and they correspond in part to the sleepiness and alertness dips we experience from morning to night. In general, we fall asleep more easily when our bedtime coincides with the natural dip in alerting signals, and we feel more refreshed when our wake time coincides with the natural rise and build-up of alerting signals. Unfortunately, 5am very rarely coincides with anyone’s biological wake time, especially in young adulthood unless one is an extreme “morning type” with a natural arousal drive that wakes them much earlier than the norm. You might know a few morning larks – those people who seem to have boundless energy in the morning while everyone else is bleary-eyed till much later. But still, 5am is a little early even for a “morning type”.

So, is it just about the early time, and not about how dark out it is? Well, it is both. Environmental light helps to entrain our internal clocks to the solar 24-h day, playing a part in triggering the timely release of agents that govern sleepiness and arousal. The onerous task of getting up at 5am in the morning in pitch darkness is helped by neither the internal drive to wake nor sunlight, which may explain why it feels like an act of sheer willpower (it indeed is).

For some, there is a light at the end of the tunnel – sunrise alarm clocks help many to wake when it’s still dark out by simulating a gradual sunrise in the bedroom (some airplanes have this feature too). Although nothing can beat waking up to a naturally sunlit morning sky, these can be very helpful for some in starting the day on a brighter note.

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