Many folks visiting Tokyo think they can save money staying in the pod room, called capsule hotels. Read about them on this guys blog;
Capsule hotels cost at least 3,000yen. All-night Saunas cost 1,200-800 yen. Both have beds. Both are noisey. So save yourself some money and be a real a SAUNA Man!
The public saunas (not gay) are used by real saavy salarymen who miss the last time but don't want to spend money on a $300 taxi ride. At a saunna you check in after 8pm work-out on the gym equipment, do the hot tub, suana, cold plunge, etc, and then crash on a lounge or deck recliner in the "Resting Room" for the night.
I used to do this so often at the "Rosco Sauna" next to my office that I bought an IC card that checked me in automatically for 450yen per visit when buying more than 10 visits. After working overtime past midnight, I would pop in my "Member Card" (sic) into a locker, pull out my yakakata and towel, hit the Unversal weight machine, then the hot tub and plop on the lounge to sleep like the baby Bejesus. They wake me up before 9am, give me a breakfast discount coupon. Then I would snarf their 300yen breakfast in the 1st floor coffee shop, and I'd be back at my desk by 9:30am looking sharper than any of my coworkers.
Don't be a Pod People... Be a SAUNA Man!
But if you're whimp, here's a list of many capsule hotels throughout tokyo