This is a short overview of what ultimates you should keep your sleep dart for as Ana and why. Keeping yourself alive is always your most important task, of course, but if you know the enemy has certain ults up you might want to keep your nade for protection instead. This guide is intended for high gold ? low diamond, since that is what I can speak for. Please note that I won?t tell you how to hit sleeps ? there?s plenty of aim guides! I canrecommend Ana Paintball though, for sleeps as well as rifling.
Naptime! High-impact sleeps, easy to hit. If enemy has this ult, keep your sleep for it always.
[BOB] (https://gfycat.com/hastysleepyarcticduck) – Huge hitbox, will be past enemy shields, will deny almost the whole ultimate, doesn?t instakill. Call out that you will sleep BOB before Ashe ults so your team doesn?t wake him up! (This might not be the case in higher ranks, but in gold-plat you will usually not have a speed Lucio nor as much rotation awareness, so denying BOB is significantly more important)
Nano?d Reinhardt & Winston – Will often go very aggressive, swinging or charging. Big hitbox. Good chance your teammates will wake him, but even that 1.5s will give your team enough time to either put significant damage in or pull back.
Death Blossom – Needs some awareness. Usually very telegraphed, with Reaper either dropping in from above (watch where he went!) or wraithing into your team instead of out. Need to be fast since it does very high DPS.
[Primal Rage] (https://gfycat.com/weightyvioletduiker) – Huge hitbox, very disruptive to your team if unchecked. Will often leap straight for supports, i.e. you. He?ll probably have used bubble before, make sure you step out of it. Like BOB, tell your team you?ll be sleeping Winston before he ults, because if he wakes he?ll just keep going.
Children, behave! – a bit harder to hit, ults with varying impact. You?ll usually want to keep your sleep for these unless it?s an emergency.
Rocket Barrage – Similar to Death Blossom, but Pharah has more angles to engage from and will instantly delete anything in front of her. If she stays at range it?s often an easy sleep since she?s spread-eagled and stationary.
[Deadeye] (https://gfycat.com/shamefulpastcicada-sleep-dart-overwatch-deadeye-ana) – Depends on the enemy McCree. If he tends to do flanking Deadeyes and your tanks don?t contest him well you should always keep your dart for it. Stationary target. If he uses it behind shields for zoning don?t bother.
[Whole Hog] (https://gfycat.com/unnaturalsolidasp) – Easy sleep if he?s aggressive, can shred your shield, kill in rooms and displace your formation. Will often push past their shields or Rein will aggress to back him up. Much higher priority if nano?d!
[Nanoblade] (https://gfycat.com/frailsimilargreyhounddog) – Different enough from normal blade to warrant its own entry. Will instadelete squishies, much tankier. Will often wipe team on its own. Your best bet is playing further behind than you usually would, so that Genji can see you (watch for snipers!). He?ll often dash in the air, receive nano and use blade, then use his 2nd dash to go straight for you. This is your best bet to sleep him. If you miss, you?ll hopefully have had enough distance to your team that he can?t reach or at least has to use another dash to close the distance to the rest.
Mother knows best – harder to hit, potentially big impact. Might need some setup, situational. Often worth keeping your sleep for.
Tank Mode – Hops and strafes around, but has a large hitbox. Will often go somewhat aggressive, giving you an opportunity for a sleep. Oneshots you if not behind shields. If woken up will just continue.
Gravitic Flux – Has a short window ? when used, before the lift activates ? where you can sleep Sigma to cancel the whole ult. Will usually activate behind cover. No effect after your team has been lifted.
[Dragonblade] (https://gfycat.com/rawplushcockroach) – Small target. If you hit him your team should be able to focus him down. Your best opportunity is hitting him when he dashes straight for you.
Other nano?d tanks – Either hard to hit due to their own abilities or not priority targets. Still good to sleep if you get the chance, can cause significant damage and are hard to kill.
You know nothing. Generally not your job. Hard to hit reliably or little impact when slept. If you have sleep, throw it, but don?t hold it for these ults specifically.
[Tactical Visor] (https://gfycat.com/leafywarmhoiho-tactical-visor-sleep-dart-overwatch] – Will be strafing like mad and be at midrange. Slim chance to hit him. Nanovisor is the same, just more.
Molten Core – Will usually shoot his load from a safe position and in a short time frame. No effect after pools are on the floor.
Rally – Armour for self and allies isn?t interrupted when slept.
Coalescence – Fully cancels her ult when slept. Hard to hit since she has a skinny hitbox and will be moving fast and erratically, often behind shields.
Valkyrie – Like Moira, hard to hit when ulting. Doesn?t cancel her ult, but can?t provide healing or boost when slept.
Call Mech – will cancel mech and leave baby D.va with no ult charge if slept during cast. She?ll usually do this from a safe location though.
[Earthshatter] (https://gfycat.com/hairyglorioushellbender) – Will be fully cancelled if slept during the cast. Cast is pretty quick though, with the distance you?ll usually be playing at almost impossible to reaction sleep.
EMP – See Reinhardt.
Sound Barrier – See Reinhardt.
Nano?d DPS – Difficulty in hitting them varies, but doesn?t change with Nano. Use sleep as you normally would essentially.
Nano?d supports – See Nano?d DPS. Lucio becomes a flanking DPS though.
The ghost watches. No interaction, your sleep simply doesn?t do anything to these. (I am aware that is not technically true for some of these, doesn?t make a difference in practice though)
Supercharger, Selfdestruct, Minefield, Graviton Surge, Meteor Strike, Dragonstrike, Riptire, Blizzard, Photon Barrier, Pulse Bomb, Infra-Sight, Nanoboost, Amplification Matrix, Transcendence
Sleep is one of the most powerful CC abilities in the game. Respect it, and make as much use of it as you can. I?ve added gifs when I had some to illustrate, I?d appreciate it if you have more examples ?