The Forbidden Zone for Sleep

It is late in the afternoon and your little one would normally be switching gears and winding down for the night. Instead, the nice soothing bedtime ritual has been traded with a surprising second wind involving bath time battles, playing chase around the house and the bed becoming the new trampoline!

This second wind is also known as the “Forbidden Zone for Sleep”!

The forbidden zone occurs in the evening during the few hours before bedtime where it is nearly impossible to fall asleep. The wakeful period of the circadian rhythm dominates the homeostatic drive creating the “forbidden sleep zone”. 

Circadian rhythms are biological cycles that repeat roughly every twenty-four hours as part of our body’s internal clock. These cycles include patterns of sleeping/waking, hunger/eating, activity/rest as well as fluctuations in body temperature and hormone levels.

Biological clocks are natural timing devices regulating the cycle of the circadian rhythms. The master clock in the brain coordinates all the biological clocks keeping them in sync.

The homeostatic sleep drive is our “drive to sleep” which is influenced by periods of sleepiness and wakefulness throughout the day. Our drive for sleep builds up in our body as our awake time increases. The drive gets stronger the longer we are awake and decreases during sleep, reaching a low after a full night of restorative sleep. The homeostatic process begins to build again after we wake for the day.

The circadian system works in opposition to the homeostatic drive making us more wakeful as the day progresses and sleepier as the night goes on. The balance between the two enables us to function consistently all day and sleep well at night.

Towards the end of the day the wakeful component of the circadian system temporarily dominates the homeostatic sleep drive causing the “forbidden zone” where children often appear sleepy in the afternoon or at dinner time and then all of a sudden become energetic and ready to do anything except sleep! At the start of the sleep phase (where you become sleepy enough to fall asleep) the circadian system switches to “sleep mode” aligning both systems and your little one will become ready for sleep.

Many parents mistakenly think their little one is not tired and keep them up later than usual. Go with the flow and try to stick to your normal routine and your little one will soon become ready for sleep.