A PERIOD(TIME(n) [WITH TIME ZONE]) value can be cast as PERIOD(TIMESTAMP[(n)] [WITH TIME ZONE]) using the CAST function.
The source time values get adjusted with respect to the session time zone displacement from the corresponding UTC value. The date portion of each result element is set to CURRENT_DATE. The hour, minute, and, second are copied from the source after the above adjustment and the timestamp value is converted to corresponding UTC value.
If the target type specifies WITH TIME ZONE and the source contains time zones, the time zone displacements from the source are copied to the corresponding result elements. If the source does not contain time zones, the current session time zone displacement is copied to both result elements.
If the target precision is higher than the source precision, trailing zeros are appended to the fractional seconds. If the target precision is lower than the source precision, an error is reported.