This is an excerpt from a book called "A Year in Paradise" by a couple
on a boat called "Witch of Endor"
http://www.yearinparadise.com/inside.html

"The bridge does open, but only between 12 midnight and five AM, and
then only if you give them 12 hour’s notice by telephone. You have to
call to make an appointment to get through the damn bridge in the
middle of the night! And then, there you would be—in total darkness in
an unfamiliar place surrounded by the lights of Alexandria, Washington
National Airport, Bolling Air Force Base, and the District of
Columbia, trying to follow a channel marked with unlighted buoys!"

It is difficult for me to believe they actually made the transit since
their description is so wide of reality.

"Total darkness... ...surrounded by lights" ???

South of the bridge heading north the lights of all the places they
mention are well upriver, on the far side of the bridge they have not
yet gone under. Not a problem.

"trying to follow a channel marked with unlighted buoys" ???

There is no weirdly winding channel to decipher like into some inlets.
It's rather straight the whole last 5 miles. Two slight bends in course,
one at 2 miles, one two miles later. A dime store compass would have
been more than sufficient, only if they are so severely nearsighted they
could see much beyond the bow.

Coming up to DC from the south:
For the 2 miles heading north to the bridge, heading is slightly west of
North. At one mile before the bridge is a flashing red marker. The
channel makers on the bridge are lighted and easy to see, as is the fact
that they are marking the peak of the extremely lit bridge. Once under
the bridge one bears slightly to the right to parallel Alexandria - on
your port.

Now heading slightly east of north it's a straight run past Alex. There
are the two airports, one major and active on the west shore, one pretty
much closed except for some minor traffic to the east. I never had
problems passing between them and seeing where I was. For the channel
there a couple of flashing reds, then a series of greens. By this time
Nat'l Airport is far to the port side, and Bolling airfield is close to
starboard. That takes care of the 2 miles north of the bridge.

Now a slight bearing to port, heading about due north, for one half
mile, well lit, leading into the very well lit Washington Channel for
the last 1/2 mile up to the marina's. Deep water.

So for the 5 miles coming up to DC: Straight for two miles with a light
at one mile and a light at the bridge. Slight bearing starboard, run two
miles, multiple well lit markers. Slight bearing to port for a half mile
straight run, well lit, into the channel to the marinas.

I have no idea why that couple in the book had so much trouble. Getting
into Annapolis is more effort. But as far as the bridge opening, not
being local they would not know about the regular arrivals (in daylight)
of the freighters (carrying newsprint I believe).

Regarding the various security restrictions, those are a different
matter. But well worth their own unique thread. The various security
forces are antsy, and much more likely to inspect then in the previous
decades. All recreational skippers are required to have proof of passing
a boating safety course. No grandfathering.