What could have happened here is that the thyroid is going hyper for a while, affecting the adrenals;
"Difficulty falling asleep is called sleep onset insomnia (SOI). It is important that cortisol is at its highest level in the morning and at its lowest level at night for normal sleep to occur, along with waking up refreshed and energized. When the cortisol balance is off, sleep patterns can be affected. High cortisol levels are typical of people suffering from Adrenal Fatigue, especially in the early stages. This happens when the adrenals are on over-drive, putting out excessive cortisol throughout the day in order to deal with the constant stress. Some of the excess cortisol even carries into the night and this will affect the ability to fall asleep, leading to SOI. At the same time, stress triggers the adrenal medulla, which then produces excessive amounts of adrenaline (a hormone responsible for the fight or flight response). A high adrenaline level can independently disturb sleep patterns as the body is on full alert. This state is commonly called being wired. High cortisol and high adrenaline can occur simultaneously and this is common for those who suffer from Adrenal Fatigue."
To help the adrenals, take magnesium (boron is important for the magnesium uptake), vit C, salt.
Vit B needed too, but can be a little tricky if adrenal problems, this caused insomnia in me; I was tired, yet wired whith a high, full pulse, palpitations.
Impossible to sleep.