Thanks for your query.
I will try my best to provide you with best possible professional recommendations to your questions.
One of the basic reasons for a spike in blood pressure levels at night is due to night-time noises which can range from traffic on the roads, to airplanes flying over-head to stray animals making a noise.
Certain researchers have found out that Blood pressure levels have also been linked to the weather and research has proven that during the daytime in hot weather the blood pressure falls but there is a marked increase in the level of systolic blood pressure at night.
Restless Leg Syndrome
and the development of cardiovascular disease
through an increase in the level of blood pressure in people at night.
I advice you to meet the physician and thorough examination of your dad is must, and he must take the medication regularly without fail and regular monitoring of his blood pressure.
Yet again, I do hope that you have found something helpful and I will be glad to answer any further queries.