Wake at 6:00 am
Four bedtimes, each one a whole number of sleep cycles before the alarm, with a quarter of an hour allowed for actually falling asleep.
Go to bed at 10:15 pm
5 cycles and 7h 30m asleep: the row nearest eight hours.
| Get into bed | Cycles | Time asleep |
|---|---|---|
| 8:45 pm | 6 cycles | 9h |
| 10:15 pm | 5 cycles | 7h 30m |
| 11:45 pm | 4 cycles | 6h |
| 1:15 am | 3 cycles | 4h 30m |
7h 30m asleep
The night nearest eight hours, laid on a clock face.
The two assumptions
Move either one and every time above moves with it. The settings follow you around the site.
What a 6:00 am alarm asks of the evening
Six o'clock sets the bedtimes at 8:45 pm, 10:15 pm, 11:45 pm and 1:15 am. The five-cycle row, at 10:15 pm, is seven and a half hours asleep, and the four-cycle row, at 11:45 pm, is the last one before midnight.
In London a 6:00 am alarm rings in daylight from about 19 April to late August, and again for the last few days of March, until the clocks go forward and put sunrise back after six. New York has it from late April to early August. In Johannesburg the alarm is light from late September to the end of February, and in Cape Town from late October to late January. Sydney has two stretches: from the middle of September to the start of October, then from the end of October to the middle of January, because the clocks going forward on the first Sunday in October push sunrise back past six for most of that month.
The six-cycle bedtime of 8:45 pm is before sunset in London from the middle of May to early August, and nowhere else in these five cities. New York's latest sunset is 8:31 pm, and the southern cities do not reach 8:45 pm at any point in the year.
The three-cycle bedtime of 1:15 am does not exist in the UK on the last Sunday of March: the clock goes from 12:59 am straight to 2:00 am. On the last Sunday of October it happens twice, as it does in New York on the first Sunday of November. On the night the clocks go forward, the other three rows each give an hour less in bed than the table says; on the night they go back, an hour more.
London's latest sunrise, 8:06 am on New Year's Day, comes two hours after this alarm. Johannesburg's, 6:56 am in late June, comes less than an hour after it.
Further afield, Tokyo is light at 6:00 am from early March to the end of October, about eight months of the year, because Japan keeps one clock all year and Tokyo sits east of the meridian it is set by. Dubai and Delhi share a window, from the middle of April to early September. Mumbai, further west on India's single clock, has only about three and a half weeks, from late May to the middle of June. Cairo has two stretches, from late March to late April and from the middle of May to early July, split by Egypt's clock change on the last Friday of April. Madrid, Singapore and Nairobi are dark at 6:00 am on every day of the year. Moscow has daylight at 6:00 am from early April to the middle of September. Chicago has it from late April to the middle of August, and Hong Kong for almost exactly the same stretch. Los Angeles has it from early May to late July, and Toronto for nearly the same weeks. São Paulo has it from the middle of September to the end of February, and Auckland only from late November to late December.
Sunrise and sunset: the NOAA solar equations, for each city centre in 2026, to the nearest minute.
Every time on this page comes from two numbers: a cycle of 90 minutes and 15 minutes between getting into bed and being asleep. Neither is a measurement of you. The reference pages say where each one comes from.
A quarter of an hour either way
If the alarm is set to something near but not exactly 6:00 am, the table for it is a page of its own.
The other direction
Already in bed and deciding when to set the alarm? The sleep-now page runs the same sum forwards from the time where you are.