Must 5e elves take a long rest?

Question

If an elf uses their trance regularly, takes short rests periodically, and is willing to forego the benefits of long rests (hit points and dice restored, spell slots and abilities restored, etc), is there anything that would require them to take a long rest regularly?

My understanding is that sleep and long rests are distinct, and that either can occur without the other. Further, there my be repercussions for a character who decides to forego sleep (e.g., exhaustion or CON checks to see if they can stay awake)? But so far I don't see any explicit penalties for avoiding a long rest in RAW...

The reason I specify an "elf" is because some DMs on fora have argued that there is no "long rest button", e.g., that once all other conditions have been met, a long rest automatically occurs. I am considering a cheesy build based on taking no long rests. By limiting my character to an elf, I can still trance to avoid exhaustion, but also avoid 8 consecutive hours that could be considered a long rest.

Answer 1

The long rest mechanic is used for the purposes of restoring resources (spell slots, hit points, class feature uses, etc) to party members. Outside of this there is no reason, mechanically, for any character to take a long rest, let alone elves.

As you mention in your question, long rest and sleep are not the same thing -- sleeping is really a roleplay choice (or something that happens when you are affected by certain spells), whereas a long rest is use of game mechanics. Of course there may be penalties for not sleeping (your DM may cause exhaustion levels to increase, for example) but there are no penalties for not long resting (aside from the lack of recovery).

Ordinarily the two concepts are generally treated as the same or at least as happening at the same time ("We go to sleep and take a long rest,") but no, as far as your question is concerned and given the constraints you have provided, there is no need for an elf, or any other character for that matter, to long rest.

Answer 2

Due to changes in later PHB printings once your elf uses the Trance feature for four hours they satisfy the conditions for a long rest, and thus take a long rest.

The recent errata change, due to updated wording in the PHB clarifies how long rests now work.

Long Rest (p. 186). The first sentence of the rule now reads, “A long rest is a period of extended downtime, at least 8 hours long, during which a character sleeps for at least 6 hours and performs no more than 2 hours of light activity, such as reading, talking, eating, or standing watch.” In addition, you regain at least one Hit Die when you finish a long rest.

The Sage Advice Compendium clarifies how this interacts with an elves Trance feature

Does the Trance trait allow an elf to finish a long rest in 4 hours? If an elf meditates during a long rest (as described in the Trance trait), the elf finishes the rest after only 4 hours. A meditating elf otherwise follows all the rules for a long rest; only the duration is changed. [This answer has been altered as a result of a tweak to the rules for a long rest, which appears in newer printings of the Player’s Handbook.]

Answer 3

Sleep/Long Rest Rules: (PHB pg 186)

A long rest is a period of extended downtime, at least 8 hours long, during which a character sleeps or performs light activity: reading, talking, eating, or standing watch for no more than 2 hours [...]

Elf Trance: (PHB pg 23)

Elves don't need to sleep. Instead, they meditate deeply, remaining semiconscious, for 4 hours a day (The Common word for such meditation is "trance."). While meditating, you can dream after a fashion; such dreams are actually mental exercises that have become reflexive through years of practice. After resting in this way, you gain the same benefit that a human does from 8 hours of sleep.

Neither of these changes the length of a long rest, but being an elf gives you more time during that long rest for standing watch or tinkering or researching or whatever.

So yeah, if you were trancing (to avoid exhaustion) and didn't need to recover HP/Hit Dice/spells, you should be fine.

Answer 4

Trance. Elves don’t need to sleep. Instead, they meditate deeply, remaining semiconscious, for 4 hours a day. (The Common word for such meditation is “trance.”) While meditating, you can dream after a fashion; such dreams are actually mental exercises that have become reflexive through years of practice. After resting in this way, you gain the same benefit that a human does from 8 hours of sleep.

(PBR 15, PHB 23)

This says how long elves must "sleep".

Long Rest

A long rest is a period of extended downtime, at least 8 hours long, during which a character sleeps or performs light activity: reading, talking, eating, or standing watch for no more than 2 hours. If the rest is interrupted by a period of strenuous activity—at least 1 hour of walking, fighting, casting spells, or similar adventuring activity— the characters must begin the rest again to gain any benefit from it.

At the end of a long rest, a character regains all lost hit points. The character also regains spent Hit Dice, up to a number of dice equal to half of the character’s total number of them (minimum of one die). For example, if a character has eight Hit Dice, he or she can regain four spent Hit Dice upon finishing a long rest.

A character can’t benefit from more than one long rest in a 24-hour period, and a character must have at least 1 hit point at the start of the rest to gain its benefits.

(PBR 67, PHB 23.)

The first paragraph limits long rest to no more than 2 hours light activity, so 6 hours of sleep, by inference.

Elves need only 4 hours of sleep, but the rule doesn't modify how long a long rest is, so the reasonable inference is that an elf might be able to take 4 hours of trance and 4 hours of light activity.

Note that a compelling argument can be made that the rule is 2 hours of light activity, and 4 hours trance... but the Trance rule doesn't allow for shorter rest times, only shorter sleep, and the long rest is already not 8 hours of sleep. Taking the 5E principles to heart, the exception is narrowly constrained... So the reasonable change is it's still 8 hours, 4 of which are trance, and any strenuous activity breaks the rest and prevents the benefits.

The DMG guidance is limited; it does note that monsters also need to eat and sleep.