Numerically described periods are not capitalised:
The preferred style is to use numerals rather than text.
Also refer to Time of day.
For time spans, use an unspaced en dash for simple spans and a spaced en dash for complex spans. A space between the the number and the abbreviation (am or pm) should be retained. For example:
When referring to time of day in prose, use either from/to or between/and in place of the en dash. For example:
The lecture will be held from 9am to 10am on Wednesday.
The seminar takes place between 10am and 4pm on Friday.
Authorised by the Executive Director, Marketing and Communications
21 January, 2014