Nagios time period and notification period

I'm having trouble getting Nagios to respect the notification_period setting for a predefined time interval.

My definition of a time period is called "sleep," as in, do not notify me between midnight and 7 am. it looks like this:

 define timeperiod{
    timeperiod_name sleep
    alias           Not Middle of Night
    sunday          07:00-23:59
    monday          07:00-23:59
    tuesday         07:00-23:59
    wednesday       07:00-23:59
    thursday        07:00-23:59
    friday          07:00-23:59
    saturday        07:00-23:59
    }

I introduced the directive for hosts as follows:

define host{
    use             linux-server,host-pnp
    host_name       server.domain.com
    alias           server.domain.com
    address         xxx.33.xxx.243
    notification_period     sleep
    }

This morning I expected to see WARNING warnings, but only after 7 in the morning. Instead, I saw them all night between 11:59 p.m. last night and 7 a.m. this morning.

My understanding from the configuration is that I should not have received emails during this time.

Did I miss something? I was hoping it would be so simple, but it did not work as expected.